OAK-614: AssertionError in MemoryNodeBuilder
keep revision up to date if disconnected

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1444013 13f79535-47bb-0310-9956-ffa450edef68
Merge branch 'trunk' of https://github.com/apache/jackrabbit-oak into trunk