subrepo: svnsubrepo._wcrev should return str after 3d6ba8c2b1b8

mercurial/subrepo.py

@@ -490,7 +490,7 b' class svnsubrepo(abstractsubrepo):'
         doc = xml.dom.minidom.parseString(output)
         entries = doc.getElementsByTagName('entry')
         if not entries:
-            return 0
+            return '0'
         return str(entries[0].getAttribute('revision')) or '0'
 
     def _wcchanged(self):