DB migration error

[Lloyd Kvam]

I was attempting to update to the latest Mediagoblin (0.11.0). This
went well except for the sqlite DB migration. The old server was
running 0.9.0 and appears to have been first setup in Dec of 2015.

bin/gmg dbupdate runs OK on the old server. It also ran OK on the new
server with an empty DB file. However, an attempt to update the old
mediagoblin.db results in:

alembic.util.exc.CommandError: Can't locate revision identified by
'38feb829c545'

Google turns up 5 results for (mediagoblin 38feb829c545), so this is
not terribly widespread, but I would appreciate any suggestions. I
realize that I may simply have to compare the revisions manually
against the old DB. 

Thanks for the work that has made this software so reliable and easy to
setup.