debugcommands: add assertions to convince pytype peer is not None

This function is moderately annoyingly defined, and peer is set up iff we're
not in raw-proto mode. That's fine, but it confuses pytype. Adding these
assertions is a low-overhead way to convince pytype we're doing reasonable
things.

Differential Revision: https://phab.mercurial-scm.org/D7407

mercurial/debugcommands.py

@@ -4161,6 +4161,7 def debugwireproto(ui, repo, path=None,
                 _(b'sending batch with %d sub-commands\n')
                 % len(batchedcommands)
             )
+            assert peer is not None
             for i, chunk in enumerate(peer._submitbatch(batchedcommands)):
                 ui.status(
                     _(b'response #%d: %s\n') % (i, stringutil.escapestr(chunk))
@@ -4241,6 +4242,7 def debugwireproto(ui, repo, path=None,
                 )
 
         elif action == b'close':
+            assert peer is not None
             peer.close()
         elif action == b'readavailable':
             if not stdout or not stderr: