safehasattr: pass attribute name as string instead of bytes

This is a step toward replacing `util.safehasattr` usage with plain `hasattr`.
The builtin function behave poorly in Python2 but this was fixed in Python3.

These change are done one by one as they tend to have a small odd to trigger
puzzling breackage.

mercurial/templateutil.py

@@ -281,7 +281,7 b' class hybrid(wrapped):'
 
     def getmember(self, context, mapping, key):
         # TODO: maybe split hybrid list/dict types?
-        if not util.safehasattr(self._values, b'get'):
+        if not util.safehasattr(self._values, 'get'):
             raise error.ParseError(_(b'not a dictionary'))
         key = unwrapastype(context, mapping, key, self._keytype)
         return self._wrapvalue(key, self._values.get(key))