posix: add a pytype suppression

This one seems a little sketchier than the others, but this will clean
up when we're Python 3-only.

Differential Revision: https://phab.mercurial-scm.org/D7276

mercurial/posix.py

@@ -323,7 +323,10 b' def checklink(path):'
                     fullpath = os.path.join(cachedir, target)
                     open(fullpath, b'w').close()
                 except IOError as inst:
-                    if inst[0] == errno.EACCES:
+                    if (
+                        inst[0]  # pytype: disable=unsupported-operands
+                        == errno.EACCES
+                    ):
                         # If we can't write to cachedir, just pretend
                         # that the fs is readonly and by association
                         # that the fs won't support symlinks. This