Merge rev 27524 from 3.3 branch.

A test here didn't clean up after a failing commit().

src/transaction/tests/test_register_compat.py

@@ -85,6 +85,10 @@ RuntimeError: commit
 1
 >>> len(cn.aborted)
 3
+
+Clean up:
+
+>>> transaction.abort()
 """
 
 import transaction