Capistrano deploy error "fatal: unable to create '.git/index.lock': File exists"
This isn’t specific to capistrano, necessarily, but I ran into it deploying.
fatal: unable to create '.git/index.lock': File exists
The fix:
Got to your project’s shared/cached-copy/.git folder and delete index.lock . It shouldn’t ever get hung up like that, but it happened to me.

Posted by Wes in