Add em.merge back into workingCopy

- we were too agressive removing this.  when creating a working copy the entity
needs to be saved after becoming the ancestor root (attributes are updated)

Author: paulcwarren

spring-versions-jpa/src/main/java/org/springframework/versions/impl/LockingAndVersioningRepositoryImpl.java

@@ -179,6 +179,7 @@ public <S extends T> S workingCopy(S currentVersion) {
         S ancestorRoot;
         if (isAnestralRoot(currentVersion)) {
             currentVersion = (S)versioner.establishAncestralRoot(currentVersion);
+            em.merge(currentVersion);
             ancestorRoot = currentVersion;
         } else {
             Object ancestorRootId = getAncestralRootId(currentVersion);