bundle: do not detect --base argument that match nothing as lack of argument With the previous version of the code, if --base did not match anything, it will be handled as if no --base was provided and will fallback to using discovery with the default path. This has two issues : - The resulting bundle won't match what the user requested, - if not default path is configured, it will crash. We now properly distinct between the two cases and if the --base query does not find any changeset, we will assume that everything under --rev needs to be sent.