Concurrent git commands on the same repo fail

[mattwynne]

Related to #210, if you run a manual fetch immediately after a connect, you'll see a failure because the background fetch triggered by the domain rule seems to be clashing with the manual fetch.

The actual error I see is this:

[server]   <-- POST /repos/smoke-test-423955FC-68A3-4A72-B4ED-B9FCBEED12D8
[server] (node:7496) UnhandledPromiseRejectionWarning: Error: Git command `config gc.pruneExpire never` returned exit code 255:
[server] error: could not lock config file config: File exists
[server]
[server]     at GitDirectory.exec (/Users/matt/projects/git-en-boite/packages/local-git/src/git_directory.ts:27:13)
[server]     at processTicksAndRejections (internal/process/task_queues.js:97:5)
[server]     at exports.handleInit (/Users/matt/projects/git-en-boite/packages/local-git/src/handlers/handleInit.ts:9:3)
[server]     at RepoFactory.open (/Users/matt/projects/git-en-boite/packages/local-git/src/repo_factory.ts:49:5)
[server]     at Function.openGitRepo (/Users/matt/projects/git-en-boite/packages/local-git/src/dugite_git_repo.ts:17:22)
[server]     at BackgroundGitRepos.openGitRepo (/Users/matt/projects/git-en-boite/packages/local-git/src/background_git_repos.ts:64:21)
[server]     at DiskRepoIndex.find (/Users/matt/projects/git-en-boite/packages/repo-index/src/disk_repo_index.ts:20:29)
[server]     at LaBoîte.fetchFromRemote (/Users/matt/projects/git-en-boite/packages/app/src/la_boîte.ts:43:18)

So this looks like at the moment it's just caused the config commands we run in handleInit which we're blindly running each time you open a repo folder. We can probably avoid this, but there might be other problems with the other git commands when we get past this. Needs more investigation.

[stale]

This issue has been automatically marked as stale because it has not had any recent activity. It will be closed if no further activity occurs. Thank you for your contributions 🙏.

[mattwynne]

We saw this again today when testing #545

[mattwynne]

OK I've caught this today with a new acceptance test. You can reproduce it with:

show_logs=1 yarn acceptance test:wip

Here's the error we see:

fatal: Unable to create '/private/var/folders/l9/95tdbmtd3_s0jh3m9hjt6sk80000gn/T/tmp-84916-93ii628SIl64/7265706f2d38323034333935352d383137302d343661302d613234302d316536353434313064626237/shallow.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.

at GitDirectory.exec (/Users/matt/projects/git-en-boite/packages/local-clones/src/git_directory.ts:24:30)