Interrupting benchmark run persists partial cache file

[FiloSottile]

I stated a benchdiff run, and then realized I had gotten it wrong and stopped it with ^C.

When I reran it, it said "skipping benchmark for ref "HEAD^" because output file exists" although the file in the cache was just a couple lines from the first benchmark.

Instead, the output should go to a temporary file and only get moved to the cache upon success.

[FiloSottile]

Relatedly, interrupting a run also leaves behind a git worktree. It would be nice if the signal was caught and a cleanup step run anyway.

[WillAbides]

Thanks. I haven't run across this before, probably because I typically use --force-base.

The next few weeks are busy for me, so I don't think I will have time to get to this for a while. If you can identify a fix, I can make time for a PR review. Otherwise it may be a while before this is fixed.