I reran https://github.com/wildfly/wildfly/pull/8961 using 5.2.2.Final.
I still see error "Could not set provided connection [org.jboss.jca.adapters.jdbc.jdk7.WrappedConnectionJDK7@53e0fe] to auto-commit mode (needed for schema generation)" and new ones like "javax.persistence.TransactionRequiredException: no transaction is in progress" and "java.lang.IllegalStateException: A JTA EntityManager cannot use getTransaction()" and "NoResultException should occur but didn't!".
Using 5.1.1-SNAPSHOT all the the test run successful. Nothing else changed in-between.