the bug here is that there is no UI message telling the user that another staging request is being processed, and no logs.
set the following portal.property
staging.lock.enabled=true
Steps to Reproduce:
1. Configured a remote staging environment that is on a basic ehcache cluster.
2. Created two Admin users with the ability to stage.
3. Created 450 pages and 400 documents via the Docs and Media portlet.
4. Published at the same time (with Michael Wine)
5. The publish completed for one user, but failed for the other. The process however
6 for the second user, a ORMException occurred (though possibly other errors would occur.
expected result: the error reported should detail that a concurrent publish is already happening.
actual result: ambiguous error is reported and a clear message in the UI is not displayed.
