Ticket #387 - managed entry sometimes doesn't delete the managed entry
    
    https://fedorahosted.org/389/ticket/387
    Resolves: Ticket #387
    Bug Description: managed entry sometimes doesn't delete the managed entry
    Reviewed by: nhosoi (Thanks!)
    Branch: master
    Fix Description: A modify just replaces the old entry in the cache with
    the new entry, and the modify code only does the cache_replace if the
    database operations succeed, so we don't have to do any cache cleanup
    in the txn retry loop.  Also cleanup some other cache usage.  If there
    is an error and ec is in the cache, we still have to remove it and restore
    the original e entry.
    Platforms tested: RHEL6 x86_64, Fedora 17
    Flag Day: no
    Doc impact: no