Please describe the problem.

annex get does not work from read-only file systems...

What steps will reproduce the problem?

$ git annex get --from=...
error: could not lock config file /.../Annex/.git/config: Read-only file system
get ... (from ...) error: could not lock config file .../Annex/.git/config: Read-only file system
  git [Param "config",Param "annex.version",Param "5"] failed
failed

What version of git-annex are you using? On what operating system?

annex.version = 3 in the remote

$ git annex version
git-annex version: 5.20140927
build flags: Assistant Webapp Webapp-secure Pairing Testsuite S3 WebDAV Inotify DBus DesktopNotify XMPP DNS Feeds Quvi TDFA CryptoHash
key/value backends: SHA256E SHA1E SHA512E SHA224E SHA384E SKEIN256E SKEIN512E SHA256 SHA1 SHA512 SHA224 SHA384 SKEIN256 SKEIN512 WORM URL
remote types: git gcrypt S3 bup directory rsync web webdav tahoe glacier ddar hook external
local repository version: 5
supported repository version: 5
upgrade supported from repository versions: 0 1 2 4

done; Fixed for V3 mode and rejected trying to support all old versions without a repo-changing upgrade process. --Joey