mq: pass qbase node instead of mq statusentry in phasedefaults

This was breaking my remotebranches extension in a completely
mystifying way, because repo.lookup was failing to resolve the
statusentry. I'm not sure how this works absent my remotebranches
extension, but doing it this way looks more correct and doesn't break
anything.

hgext/mq.py

@@ -3133,7 +3133,7 b' def qqueue(ui, repo, name=None, **opts):'
 def mqphasedefaults(repo, roots):
     """callback used to set mq changeset as secret when no phase data exists"""
     if repo.mq.applied:
-        qbase = repo[repo.mq.applied[0]]
+        qbase = repo[repo.mq.applied[0].node]
         roots[phases.secret].add(qbase.node())
     return roots