CRM-13085 - Fix premature transaction commit (due to ACL)

For example, CRM_Core_TransactionTest::testRollback_BaoCreate_1xOuter was failing. The patch in cded6e4 fixes it. 

I checked api_v3_ACLCachingTest or api_v3_ACLPermissionTest (on my workstation) and didn't find any regressions.