Finger memory, or just a shell configured to run `git status` before every command, as some people have.

And besides a Mercurial repo, it could also be a tarball or zip file…

Quite a dangerous situation.

I’ve done that a few times. I’ve typed “git foo” while mentally thinking about “svn foo”, and after a few hours working on a project that still uses svn I will start making the opposite substitution too.

We use the grunt build tool. More than a handful of times, I've tried to get grunt to do a merge, or git to build the app.