### Please describe the problem.

git-annex-view fails with an error message that `viewindex.lock` exists and another git process is running in the repository.
The problem appears even with newly initialized repositories.

### What steps will reproduce the problem?

The steps I followed to reproduce the problem:

[[!format sh """
cd /tmp
mkdir testgit
cd testgit
git init
git annex init
echo 123 > test1
echo 456 > test2
git annex add test1 test2
git commit -m 'initial commit'
git annex metadata -s test=test1 test1
git annex metadata -s test=test2 test2
git annex view test=test1
"""]]

Note: The problem does not appear with git-annex version 7.20190819+git2-g908476a9b-1~ndall+1 but it appears with 8.20201007-g903b2f1.


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

I could reproduce the problem at two different machines, both with Ubuntu 18.04 LTS.
`git-annex` was installed via conda using the command `conda install -c conda-forge git-annex`

```
git-annex version: 8.20201007-g903b2f1
build flags: Assistant Webapp Pairing Inotify DBus DesktopNotify TorrentParser MagicMime Feeds Testsuite S3 WebDAV
dependency versions: aws-0.22 bloomfilter-2.0.1.0 cryptonite-0.26 DAV-1.3.4 feed-1.3.0.1 ghc-8.8.4 http-client-0.6.4.1 persistent-sqlite-2.10.6.2 torrent-10000.1.1 uuid-1.3.13 yesod-1.6.1.0
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 BLAKE2B256E BLAKE2B256 BLAKE2B512E 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 httpalso hook external
operating system: linux x86_64
supported repository versions: 8
upgrade supported from repository versions: 0 1 2 3 4 5 6 7
local repository version: 8
```


### Please provide any additional information below.

Here is the complete error message:

[[!format sh """
view (searching...) fatal: Unable to create '/tmp/mytmp/.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
"""]]

### 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)
git-annex is an awesome tool! Really appreciate your work and everything else works great!

> Thank you for reporting, I've fixed this reversion and am also going to
> add something like that to the test suite, which lacked any testing of
> views. [[done]] --[[Joey]]
