Comment 10 for bug 415508

John's patch

http://bazaar.launchpad.net/~jameinel/bzr/1.17-content-filtering-commit/revision/4530

seems reasonable, but seems to indicate that we'd want a test for record_entry_contents (or a larger function, up to commit), checking that it gets the canonical size from the tree, not the convenient size. Even if this interface is renamed, there'd still be a chance commit was using the wrong one and we ought to test it.