### Please describe the problem.
After successfully adding tags to files, I'm unable to view them.  I paste the input and output to reproduce the problem below.

### What steps will reproduce the problem?

    $ git annex init
    init
      Detected a filesystem without fifo support.

      Disabling ssh connection caching.

      Detected a crippled filesystem.
    (scanning for unlocked files...)

      Entering an adjusted branch where files are unlocked as this filesystem does not support locked files.

    Switched to branch 'adjusted/master(unlocked)'
    ok
    (recording state in git...)

    $ touch test-file.txt

    $ git annex add .
    add test-file.txt
    ok
    (recording state in git...)

    $ git commit -a -m "Adds a file."
    warning: LF will be replaced by CRLF in test-file.txt.
    The file will have its original line endings in your working directory
    [adjusted/master(unlocked) b19bcbb] Adds a file.
     1 file changed, 1 insertion(+)
     create mode 100644 test-file.txt

    $ git annex metadata test-file.txt -t a -t b -t c
    metadata test-file.txt
      lastchanged=2021-03-17@18-31-54
      tag=a
      tag=b
      tag=c
      tag-lastchanged=2021-03-17@18-31-54
    ok
    (recording state in git...)

    $ git annex view tag=*
    view (searching...) fatal: Unable to create 'D:\test-dir\.git\annex\viewindex.lock': File exists.

    Another git process seems to be running in this repository, e.g.
    an editor opened by 'git commit'. Please make sure all processes
    are terminated then try again. If it still fails, a git process
    may have crashed in this repository earlier:
    remove the file manually to continue.

    git-annex: failed to read sha from git write-tree
    CallStack (from HasCallStack):
      error, called at .\Git\Sha.hs:23:15 in main:Git.Sha
    failed
    git-annex: view: 1 failed

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

    $ git annex version
    git-annex version: 8.20200815-g335aae266
    build flags: Assistant Webapp Pairing S3 WebDAV TorrentParser Feeds Testsuite
    dependency versions: aws-0.21.1 bloomfilter-2.0.1.0 cryptonite-0.25 DAV-1.3.4 feed-1.2.0.1 ghc-8.6.5 http-client-0.5.14 persistent-sqlite-2.9.3 torrent-10000.1.1 uuid-1.3.13 yesod-1.6.0.1
    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 BLAKE2B256EBLAKE2B512E BLAKE2B512 BLAKE2B160E BLAKE2B160 BLAKE2B224E BLAKE2B224 BLAKE2B384E BLAKE2B384 BLAKE2BP512E BLAKE2BP512 BLAKE2S256E BLAKE2S256 BLAKE2S160E BLAKE2S160 BLAKE2S224E BLAKE2S224 BLAKE2SP256E BLAKE2SP256 BLAKE2SP224E BLAKE2SP224 SHA1E SHA1 MD5E MD5 WORM URL X*
    remote types: git gcrypt p2p S3 bup directory rsync web bittorrent webdav adb tahoe glacier ddar git-lfs hook external
    operating system: mingw32 x86_64
    supported repository versions: 8
    upgrade supported from repository versions: 2 3 4 5 6 7
    local repository version: 8

And I'm using the Git Bash terminal on Windows 10 Pro.  

### Please provide any additional information below.

[[!format sh """
# If you can, paste a complete transcript of the problem occurring here.
# If the problem is with the git-annex assistant, paste in .git/annex/daemon.log


# End of transcript or log.
"""]]

### 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)
I'm pretty hyped about git annex.  I finally sat down and started backing up my data on different drives and git annex is about the perfect solution.  Or at least it does everything I want it to (especially if the above tagging issue can be resolved).  I've even thought about writing little cli apps over it, like an ejournal or recipe organizer.  


> [[fixed|done]] already some time ago --[[Joey]]
