When using a local git remote on eg a removable drive, error messages don't
make clear if the problem occurred in the local git repo or the remote
repo.

For example, I was copying files to a removable drive and got an error
about a broken git object, but it was not clear which repo had the broken
object in it.

This should be fixable by eg, catching all exceptions when running Annex
operations on a remote, adding its path to the message and rethrowing.
--[[Joey]]

[[!tag confirmed]]
