To be completely clear: I'm not going to accept any features upstream which zero customers are interested in. It doesn't matter if they're simple or complicated. If no customers want it, it isn't coming upstream.

I don't expect any sophisticated git-worktree support. This is a simple change that allows arc get-config/set-config to work correctly when invoked from a worktree. It might also fix some other cases where arc expects $identity->localMetaDir to be a directory which previously wasn't the case for worktrees.

Adding overflow-wrap: anywhere appears to fix this without breaking anything.

There's currently no customer interest in worktree support. The use cases in T9924 seem flimsy to me so I don't currently plan to support worktrees in the absence of customer interest. See also ArcanistGitWorkingCopy.

• fix $vcs -> $vcs_type

PHI1816 would also like dimensional coverage: coverage by language; coverage by team/owner. This is perhaps worth considering in how coverage is aggregated.