It would be great when diagnosing issues to know the version of a particular library that git-annex is compiled with.

Because there are so many dependencies though, perhaps only the libraries corresponding to a build flag should be displayed, so instead of

~ λ git annex version
git-annex version: 6.20170321-g4642912
build flags: Assistant Webapp Pairing Testsuite S3(multipartupload)(storageclasses) WebDAV Inotify ConcurrentOutput TorrentParser Feeds Quvi
key/value backends: SHA256E SHA256 SHA512E SHA512 SHA224E SHA224 SHA384E SHA384 SHA3_256E SHA3_256 SHA3_512E SHA3_512 SHA3_224E SHA3_224 SHA3_384E SHA3_384 SKEIN256E SKEIN256 SKEIN512E SKEIN512 SHA1E SHA1 MD5E MD5 WORM URL
remote types: git gcrypt p2p S3 bup directory rsync web bittorrent webdav tahoe glacier ddar hook external

It would show:

~ λ git annex version
git-annex version: 6.20170321-g4642912
build flags: ...etc... TorrentParser-1.2.1 Feeds-2.3.1 Quvi-1.0.0
key/value backends: SHA256E SHA256 SHA512E SHA512 SHA224E SHA224 SHA384E SHA384 SHA3_256E SHA3_256 SHA3_512E SHA3_512 SHA3_224E SHA3_224 SHA3_384E SHA3_384 SKEIN256E SKEIN256 SKEIN512E SKEIN512 SHA1E SHA1 MD5E MD5 WORM URL
remote types: git gcrypt p2p S3 bup directory rsync web bittorrent webdav tahoe glacier ddar hook external

Well, I think better not to complicate the build flags list, which the user may want to refer to, with this. Also, there should be a way to indicate versions for libraries that don't have a build flag, when the version is a common question. So, let's add it as a separate line of data. done --Joey