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

@@ -301,7 +301,7 b' class hybrid(wrapped):'
     def _wrapvalue(self, key, val):
         if val is None:
             return
-        if util.safehasattr(val, b'_makemap'):
+        if util.safehasattr(val, '_makemap'):
             # a nested hybrid list/dict, which has its own way of map operation
             return val
         return hybriditem(None, key, val, self._makemap)