match: suppress error about subscripting an exception

I get the sense I should file a bug about subscripting Exception subclasses.

Differential Revision: https://phab.mercurial-scm.org/D7286

mercurial/match.py

@@ -345,7 +345,10 b' def _donormalize(patterns, default, root'
                 ):
                     kindpats.append((k, p, source or pat))
             except error.Abort as inst:
-                raise error.Abort(b'%s: %s' % (pat, inst[0]))
+                raise error.Abort(
+                    b'%s: %s'
+                    % (pat, inst[0])  # pytype: disable=unsupported-operands
+                )
             except IOError as inst:
                 if warn:
                     warn(