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/hgweb/hgweb_mod.py

@@ -478,7 +478,7 b' class hgweb:'
 
         except (error.LookupError, error.RepoLookupError) as err:
             msg = pycompat.bytestr(err)
-            if util.safehasattr(err, b'name') and not isinstance(
+            if util.safehasattr(err, 'name') and not isinstance(
                 err, error.ManifestLookupError
             ):
                 msg = b'revision not found: %s' % err.name