Please describe the problem.

Happens as a part of our test for datalad-archives external special remote we drop/get the file we just added to git-annex from a tarball.

It works fine on Linux, and from todays fix 8.20201007-144-g7245a9ed5 we no longer stall, and proceed to that drop. But drop fails claiming that the content is locked. I have checked processes - there is no some other git annex hanging around and .lck even doesn't exist before we call drop.

    (datalad-3) C:\Users\DataLad\AppData\Local\Temp\datalad_temp_tree_ythgiyjt\a\d>dir ..\..\.git\annex\objects\662\c6f\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc\                                                     
     Volume in drive C has no label.                                                                                                                                                                                                                           
     Volume Serial Number is AC6C-BABE                                                                                                                                                                                                                         

     Directory of C:\Users\DataLad\AppData\Local\Temp\datalad_temp_tree_ythgiyjt\.git\annex\objects\662\c6f\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc                                                                  

    11/02/2020  05:17 PM    <DIR>          .                                                                                                                                                                                                                   
    11/02/2020  05:17 PM    <DIR>          ..                                                                                                                                                                                                                  
    11/02/2020  05:17 PM                 3 SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc               1 File(s)              3 bytes                                                                                      
                               2 Dir(s)  23,168,851,968 bytes free                                                                                                                                                                                             

but then it is created by drop:

    (datalad-3) C:\Users\DataLad\AppData\Local\Temp\datalad_temp_tree_ythgiyjt\a\d>git annex drop --debug -- a.datc                                                                                                                                            
    [2020-11-02 17:21:26.8245443] process [5128] read: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","symbolic-ref","-q","HEAD"]                                                                                                    
    [2020-11-02 17:21:26.8393936] process [5128] done ExitSuccess                                                                                                                                                                                              
    [2020-11-02 17:21:26.8393936] process [1452] read: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","show-ref","refs/heads/adjusted/dl-test-branch(unlocked)"]                                                                     
    [2020-11-02 17:21:26.8860693] process [1452] done ExitSuccess                                                                                                                                                                                              
    [2020-11-02 17:21:26.8860693] process [2004] read: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","ls-files","--stage","-z","--","a.datc"]                                                                                       
    [2020-11-02 17:21:26.9331701] process [3452] chat: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","cat-file","--batch-check=%(objectname) %(objecttype) %(objectsize)","--buffer"]                                               
    [2020-11-02 17:21:26.9501808] process [4632] chat: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","cat-file","--batch=%(objectname) %(objecttype) %(objectsize)","--buffer"]                                                     
    [2020-11-02 17:21:26.9501808] process [2920] read: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","show-ref","git-annex"]                                                                                                        
    [2020-11-02 17:21:27.0113712] process [2920] done ExitSuccess                                                                                                                                                                                              
    [2020-11-02 17:21:27.0113712] process [976] read: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","show-ref","--hash","refs/heads/git-annex"]                                                                                     
    [2020-11-02 17:21:27.0580403] process [976] done ExitSuccess                                                                                                                                                                                               
    [2020-11-02 17:21:27.0580403] process [8] read: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","log","refs/heads/git-annex..6217b1e92de175374dcb552d2bddee0b785073ce","--pretty=%H","-n1"]                                       
    [2020-11-02 17:21:27.1363275] process [8] done ExitSuccess                                                                                                                                                                                                 
    [2020-11-02 17:21:27.1363275] process [6948] chat: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","hash-object","-w","--stdin-paths","--no-filters"]                                                                             
    [2020-11-02 17:21:27.1675675] process [1728] chat: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","cat-file","--batch"]                                                                                                          
    [2020-11-02 17:21:27.1675675] process [4840] chat: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","cat-file","--batch-check=%(objectname) %(objecttype) %(objectsize)"]                                                          
    [2020-11-02 17:21:27.1834634] process [7832] feed: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","update-index","-z","--index-info"]                                                                                            
    [2020-11-02 17:21:27.2146236] process [6244] read: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","diff-index","--raw","-z","-r","--no-renames","-l0","--cached","refs/heads/git-annex","--"]                                    
    [2020-11-02 17:21:27.2769931] process [6244] done ExitSuccess                                                                                                                                                                                              
    [2020-11-02 17:21:27.3111859] process [7832] done ExitSuccess                                                                                                                                                                                              
    [2020-11-02 17:21:27.3238724] process [5528] chat: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","cat-file","--batch=%(objectname) %(objecttype) %(objectsize)","--buffer"]                                                     
    [2020-11-02 17:21:27.3864742] process [8556] chat: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","check-attr","-z","--stdin","annex.backend","annex.numcopies","annex.largefiles","--"]                                         
    [2020-11-02 17:21:27.4331328] process [1100] chat: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","cat-file","--batch"]                                                                                                          
    [2020-11-02 17:21:27.4331328] process [3516] chat: git ["--git-dir=..\\..\\.git","--work-tree=..\\..","--literal-pathspecs","cat-file","--batch-check=%(objectname) %(objecttype) %(objectsize)"]                                                          
    drop a.datc                                                                                                                                                                                                                                                
    git-annex: content is locked                                                                                                                                                                                                                               
    failed                                                                                                                                                                                                                                                     
    [2020-11-02 17:21:27.5114868] process [1100] done ExitSuccess                                                                                                                                                                                              
    [2020-11-02 17:21:27.5114868] process [3516] done ExitSuccess                                                                                                                                                                                              
    [2020-11-02 17:21:27.5114868] process [8556] done ExitSuccess                                                                                                                                                                                              
    [2020-11-02 17:21:27.5275735] process [6948] done ExitSuccess                                                                                                                                                                                              
    [2020-11-02 17:21:27.5422938] process [5528] done ExitSuccess                                                                                                                                                                                              
    [2020-11-02 17:21:27.5422938] process done ExitSuccess                                                                                                                                                                                                     
    [2020-11-02 17:21:27.5422938] process done ExitSuccess                                                                                                                                                                                                     
    [2020-11-02 17:21:27.5422938] process [4632] done ExitSuccess                                                                                                                                                                                              
    [2020-11-02 17:21:27.5422938] process [3452] done ExitSuccess                                                                                                                                                                                              
    [2020-11-02 17:21:27.5422938] process [2004] done ExitSuccess                                                                                                                                                                                              
    [2020-11-02 17:21:27.5422938] process done ExitSuccess                                                                                                                                                                                                     
    git-annex: drop: 1 failed                                                                                                                                                                                                                                  


    (datalad-3) C:\Users\DataLad\AppData\Local\Temp\datalad_temp_tree_ythgiyjt\a\d>dir ..\..\.git\annex\objects\662\c6f\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc\                                                     
     Volume in drive C has no label.                                                                                                                                                                                                                           
     Volume Serial Number is AC6C-BABE                                                                                                                                                                                                                         

     Directory of C:\Users\DataLad\AppData\Local\Temp\datalad_temp_tree_ythgiyjt\.git\annex\objects\662\c6f\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc                                                                  

    11/02/2020  05:21 PM    <DIR>          .                                                                                                                                                                                                                   
    11/02/2020  05:21 PM    <DIR>          ..                                                                                                                                                                                                                  
    11/02/2020  05:17 PM                 3 SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc                                                                                                                                   
    11/02/2020  05:21 PM                 0 SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc.lck                                                                                                                               
                               2 File(s)              3 bytes                                                                                                                                                                                                  
                               2 Dir(s)  23,168,679,936 bytes free         

so it seems that drop somehow steps on its own feet and gets freaked out.

Here is also some dump from procmon captured during drop, and filtered on this lck file name

5:07:49.2392479 PM  git-annex.exe   2144    CreateFile  C:\Users\DataLad\AppData\Local\Temp\datalad_temp_tree_j7pvlyz2\.git\annex\objects\662\c6f\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc.lck   SUCCESS Desired Access: Generic Read/Write, Disposition: OpenIf, Options: Synchronous IO Non-Alert, Non-Directory File, Attributes: N, ShareMode: Read, Write, Delete, AllocationSize: 0, OpenResult: Opened    File System 8228    8664
5:07:49.2393198 PM  git-annex.exe   2144    QueryInformationVolume  C:\Users\DataLad\AppData\Local\Temp\datalad_temp_tree_j7pvlyz2\.git\annex\objects\662\c6f\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc.lck   SUCCESS VolumeCreationTime: 10/22/2020 2:55:22 PM, VolumeSerialNumber: AC6C-BABE, SupportsObjects: True, VolumeLabel:   File System 8228    8664
5:07:49.2393295 PM  git-annex.exe   2144    QueryAllInformationFile C:\Users\DataLad\AppData\Local\Temp\datalad_temp_tree_j7pvlyz2\.git\annex\objects\662\c6f\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc.lck   BUFFER OVERFLOW CreationTime: 11/2/2020 5:02:41 PM, LastAccessTime: 11/2/2020 5:04:56 PM, LastWriteTime: 11/2/2020 5:04:56 PM, ChangeTime: 11/2/2020 5:04:56 PM, FileAttributes: A, AllocationSize: 0, EndOfFile: 0, NumberOfLinks: 1, DeletePending: False, Directory: False, IndexNumber: 0x2e000000015258, EaSize: 0, Access: Generic Read/Write, Position: 0, Mode: Synchronous IO Non-Alert, AlignmentRequirement: Word    File System 8228    8664
5:07:49.2393613 PM  git-annex.exe   2144    QueryInformationVolume  C:\Users\DataLad\AppData\Local\Temp\datalad_temp_tree_j7pvlyz2\.git\annex\objects\662\c6f\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc.lck   SUCCESS VolumeCreationTime: 10/22/2020 2:55:22 PM, VolumeSerialNumber: AC6C-BABE, SupportsObjects: True, VolumeLabel:   File System 8228    8664
5:07:49.2393740 PM  git-annex.exe   2144    QueryAllInformationFile C:\Users\DataLad\AppData\Local\Temp\datalad_temp_tree_j7pvlyz2\.git\annex\objects\662\c6f\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc.lck   BUFFER OVERFLOW CreationTime: 11/2/2020 5:02:41 PM, LastAccessTime: 11/2/2020 5:04:56 PM, LastWriteTime: 11/2/2020 5:04:56 PM, ChangeTime: 11/2/2020 5:04:56 PM, FileAttributes: A, AllocationSize: 0, EndOfFile: 0, NumberOfLinks: 1, DeletePending: False, Directory: False, IndexNumber: 0x2e000000015258, EaSize: 0, Access: Generic Read/Write, Position: 0, Mode: Synchronous IO Non-Alert, AlignmentRequirement: Word    File System 8228    8664
5:07:49.2394246 PM  git-annex.exe   2144    QueryStandardInformationFile    C:\Users\DataLad\AppData\Local\Temp\datalad_temp_tree_j7pvlyz2\.git\annex\objects\662\c6f\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc.lck   SUCCESS AllocationSize: 0, EndOfFile: 0, NumberOfLinks: 1, DeletePending: False, Directory: False   File System 8228    8664
5:07:49.2394500 PM  git-annex.exe   2144    SetEndOfFileInformationFile C:\Users\DataLad\AppData\Local\Temp\datalad_temp_tree_j7pvlyz2\.git\annex\objects\662\c6f\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc.lck   SUCCESS EndOfFile: 0    File System 8228    8664
5:07:49.2395339 PM  git-annex.exe   2144    SetAllocationInformationFile    C:\Users\DataLad\AppData\Local\Temp\datalad_temp_tree_j7pvlyz2\.git\annex\objects\662\c6f\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc.lck   SUCCESS AllocationSize: 0   File System 8228    8664
5:07:49.2395801 PM  git-annex.exe   2144    CloseFile   C:\Users\DataLad\AppData\Local\Temp\datalad_temp_tree_j7pvlyz2\.git\annex\objects\662\c6f\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc\SHA256E-s3--a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3.datc.lck   SUCCESS     File System 8228    8664

so it seems to happily create that file.