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

@@ -341,7 +341,7 b' class hybrid(wrapped):'
     def tovalue(self, context, mapping):
         # TODO: make it non-recursive for trivial lists/dicts
         xs = self._values
-        if util.safehasattr(xs, b'get'):
+        if util.safehasattr(xs, 'get'):
             return {k: unwrapvalue(context, mapping, v) for k, v in xs.items()}
         return [unwrapvalue(context, mapping, x) for x in xs]