Catch HTTPException when reading from remote http repository. If the server dies very early, an httplib.IncompleteRead exception may be raised, because httplib can't read a single byte. Catching all HTTPException subclasses here will prevent ugly backtraces for similar things, too.

Is there an error message when trying to diff non-existing files?
found: No such file or directory
not: No such file or directory
Is there an error message when trying to add non-existing files?
found: No such file or directory
not: No such file or directory