Change ensureFlowRevision to use Status and not check summary
In the course of debugging the import script we decided to add
some more detailed logging, including of the ensureFlowRevision call.
Erik suggested I change it to return a status.
In the course of looking at that, I decided to remove the edit summary
check, since it is not reliable. Users can set this summary on normal
Imports must be to non-existent pages. Before, allowCreation was
failing, but the test passed anyway because it never verified
the commit succeeded (and the fail-early is new).