[MERGE] add -c option to merge command (#141368)

[Ian Clatworthy]

Alexander Belchenko wrote:

>>> +    def assertDirectoryContent(self, directory, entries, message=''):
>>> +        """Assert whether entries (files or directories) are exist
>>> +        in some directory. It's also check that there is no extra
>>> +        entries.
>>> +        """
>> As this is an internal method, I'd prefer a leading underscore on the
>> name. 
> 
> I disagree here. grep output for 'def .?assert' is very big and there are
> a lot of Test* classes that define their own domain-specific assert methods.
> And there are a lot methods without underscore in name and
> only 2 methods with underscores:
> 
> bzrlib\tests\test_counted_lock.py:56:     def _assert_locked(self):
> bzrlib\tests\test_counted_lock.py:60:     def _assert_not_locked(self):

Sure. Go ahead and merge without that change. It was a minor preference
in this case.

Ian C.