typing: add several assertions to dirstatemap to appease pytype I think it's been mentioned in IRC that these can't be None in this case. This fixes: File "/mnt/c/Users/Matt/hg/mercurial/dirstatemap.py", line 213, in addfile: unsupported operand type(s) for &: 'None' and 'int' [unsupported-operands] No attribute '__and__' on None or '__rand__' on int Called from (traceback): line 290, in reset_state File "/mnt/c/Users/Matt/hg/mercurial/dirstatemap.py", line 214, in addfile: unsupported operand type(s) for &: 'None' and 'int' [unsupported-operands] No attribute '__and__' on None or '__rand__' on int Called from (traceback): line 290, in reset_state Differential Revision: https://phab.mercurial-scm.org/D11235