py3: make adefaults keys str to be compatible with getattr

getattr passes a str value of the attribute to be looked and keys in adefaults
dict are bytes which resulted in AttributeError. This patch abuses r'' to
make the keys str.

mercurial/dispatch.py

@@ -479,7 +479,8 b' class cmdalias(object):'
         return aliasargs(self.fn, args)
 
     def __getattr__(self, name):
-        adefaults = {'norepo': True, 'optionalrepo': False, 'inferrepo': False}
+        adefaults = {r'norepo': True,
+                     r'optionalrepo': False, r'inferrepo': False}
         if name not in adefaults:
             raise AttributeError(name)
         if self.badalias or util.safehasattr(self, 'shell'):