Fix a small corner of log behaviour.
If invoked with no arguments in a subdirectory of the repo root, it
should print the history of the repository as a whole.
Is there an error message when trying to diff non-existing files?
not: No such file or directory
found: No such file or directory
Is there an error message when trying to add non-existing files?
not: No such file or directory
found: No such file or directory