### Please describe the problem.

With a v6 repo, if I unlock an annex file, change it, and then add it back, the annex object is writeable.

### What steps will reproduce the problem?

    git init tmp-v6 && cd tmp-v6
    git annex init --version=6
    echo foo >foo && git annex add foo && git commit -m'add foo'
    git annex unlock foo
    echo more >>foo && git annex add foo && git commit -m'modify foo'
    ls -l $(readlink foo)
    # -rw-r--r-- 1 kyle kyle 9 Aug 29 17:18 .git/annex/objects/60/QW/SHA256E-s9--323409d9a706bc08d0b2c7f71309e21a757367c81cffb405a88e61749d79952d/SHA256E-s9--323409d9a706bc08d0b2c7f71309e21a757367c81cffb405a88e61749d79952d

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

    git annex version

    # git-annex version: 6.20180808-gdad627fa9
    # build flags: Assistant Webapp Pairing S3(multipartupload)(storageclasses) WebDAV Inotify ConcurrentOutput TorrentParser Feeds Testsuite
    # dependency versions: aws-0.17.1 bloomfilter-2.0.1.0 cryptonite-0.23 DAV-1.3.1 feed-0.3.12.0 ghc-8.0.2 http-client-0.5.7.0 persistent-sqlite-2.6.2 torrent-10000.1.1 uuid-1.3.13 yesod-1.4.5
    # 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 BLAKE2B256E BLAKE2B256 BLAKE2B512E BLAKE2B512 BLAKE2B160E BLAKE2B160 BLAKE2B224E BLAKE2B224 BLAKE2B384E BLAKE2B384 BLAKE2S256E BLAKE2S256 BLAKE2S160E BLAKE2S160 BLAKE2S224E BLAKE2S224 BLAKE2SP256E BLAKE2SP256 BLAKE2SP224E BLAKE2SP224 SHA1E SHA1 MD5E MD5 WORM URL
    # remote types: git gcrypt p2p S3 bup directory rsync web bittorrent webdav adb tahoe glacier ddar hook external
    # operating system: linux x86_64
    # supported repository versions: 3 5 6
    # upgrade supported from repository versions: 0 1 2 3 4 5
    # local repository version: 6

Debian Stretch, but building git-annex from source with `stack build`.

### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)

Yes, everyday.  Thank you for git-annex :-)

> [[fixed|done]] --[[Joey]]
