has been changed recently and now this default setting is very awkward
to change for the dgit user.
+ New checks and improved behaviours:
+ * In dgit sbuild, check that the set of .changes files found is as we
+ expect, before calling mergechanges
+
Bugfixes:
* When cleaning up after failed clone, stat the to-be-cleaned-up
directory before running rmtree on it. Closes:#796773.