hg: explicitly check that peer lookup object has instance() if call failed If a "thing" is callable but raises TypeError for some reason, a callable object would be returned. Thereafter, unfriendly traceback would be displayed: Traceback (most recent call last): ... File "mercurial/hg.pyc", line 119, in _peerorrepo obj = _peerlookup(path).instance(ui, path, create) AttributeError: 'function' object has no attribute 'instance' Instead, we should show the reason why "thing(path)" didn't work: Traceback (most recent call last): ... File "hggit/__init__.py", line 89, in _local p = urlcls(path).localpath() TypeError: 'NoneType' object is not callable If a "thing" is not callable, it must be a module or an object that implements instance(). If that module didn't have instance(), the error message would be "<unloaded module 'foo'> object is not callable". It doesn't make perfect sense, but it isn't so bad as it can blame which module went wrong.