tr-summary: keep a weakref to the unfiltered repository

Repoview can have a different life cycle, causing issue in some corner
cases. The particular instance that revealed this comes from localpeer. The
localpeer hold a reference to the unfiltered repository, but calling 'local()'
will create an on-demand 'visible' repoview. That repoview can be garbaged
collected any time. Here is a simplified step by step reproduction::

    1) tr = peer.local().transaction('foo')
    2) tr.close()

After (1), the repoview object is garbage collected, so weakref used in (2)
point to nothing.


Thanks to Sean Farley for helping raising and debugging this issue.

mercurial/scmutil.py

@@ -1233,9 +1233,17 @@ def registersummarycallback(repo, otr, txnname=''):
 
     def reportsummary(func):
         """decorator for report callbacks."""
-        reporef = weakref.ref(repo)
+        # The repoview life cycle is shorter than the one of the actual
+        # underlying repository. So the filtered object can die before the
+        # weakref is used leading to troubles. We keep a reference to the
+        # unfiltered object and restore the filtering when retrieving the
+        # repository through the weakref.
+        filtername = repo.filtername
+        reporef = weakref.ref(repo.unfiltered())
         def wrapped(tr):
             repo = reporef()
+            if filtername:
+                repo = repo.filtered(filtername)
             func(repo, tr)
         newcat = '%2i-txnreport' % len(categories)
         otr.addpostclose(newcat, wrapped)