revision: Don't mark as a rerun unless explicitly set

Whenever we are duplicating metadata about a revision let's clean the
rerun state.

Without this all revisions to series that had been rerun were stuck in
the "this is a rerun" state, even if updated version of the patches were
sent.

Fixes #31

Signed-off-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
1 job for master in 1 minute and 31 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Test
passed #1871534
test

00:01:31