localrepo: filter unknown nodes from the phasecache on destroyed

When commit is followed by strip (qrefresh), phasecache contains nodes that were
removed from the changelog. Since phasecache is filecached with .hg/store/phaseroots
which doesn't change as a result of stripping, we have to filter it manually.

If we don't write it immediately, the next time it is read from disk the nodes
will be filtered again. That's what happened before, but there's no reason not
to write it immediately.

The change in test-keyword.t is caused by the above.

mercurial/localrepo.py

@@ -1425,6 +1425,18 b' class localrepository(object):'
             cache.update(self, ctxgen)
             cache.write(self)
 
+        # When one tries to:
+        # 1) destroy nodes thus calling this method (e.g. strip)
+        # 2) use phasecache somewhere (e.g. commit)
+        #
+        # then 2) will fail because the phasecache contains nodes that were
+        # removed. We can either remove phasecache from the filecache,
+        # causing it to reload next time it is accessed, or simply filter
+        # the removed nodes now and write the updated cache.
+        if '_phasecache' in self._filecache:
+            self._phasecache.filterunknown(self)
+            self._phasecache.write()
+
         # Ensure the persistent tag cache is updated.  Doing it now
         # means that the tag cache only has to worry about destroyed
         # heads immediately after a strip/rollback.  That in turn

tests/test-keyword.t

@@ -578,7 +578,6 b' Commit and show expansion in original an'
   $ hg --debug commit -ma2c -d '1 0' -u 'User Name <[e-mail]>'
   c
    c: copy a:0045e12f6c5791aac80ca6cbfd97709a88307292
-  removing unknown node 40a904bbbe4c from 1-phase boundary
   overwriting c expanding keywords
   committed changeset 2:25736cf2f5cbe41f6be4e6784ef6ecf9f3bbcc7d
   $ cat a c
@@ -749,7 +748,6 b' Commit with multi-line message and custo'
 
   $ hg --debug commit -l log -d '2 0' -u 'User Name <[e-mail]>'
   a
-  removing unknown node 40a904bbbe4c from 1-phase boundary
   overwriting a expanding keywords
   committed changeset 2:bb948857c743469b22bbf51f7ec8112279ca5d83
   $ rm log