The next iteration of ZODB 3.3 doesn't implicitly begin a new

transaction when a commit() fails.  One test here provoked a
failing commit(), which caused a later test to fail.  Repaired
by simply abort()'ing the failed transaction.

src/transaction/tests/test_register_compat.py

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