http://codereview.appspot.com/975/diff/1/4
File updater.py (right):

http://codereview.appspot.com/975/diff/1/4#newcode1
Line 1: import logging
move all these changes to display/handler_update.py :) 

(you may need to svn up)

http://codereview.appspot.com/975/diff/1/4#newcode22
Line 22: for m in re.finditer('([+-])([a-zA-Z0-9]{32})', data):
a-fA-F

also lowercase before adding / looking up

http://codereview.appspot.com/975/diff/1/4#newcode23
Line 23: op, hash = m.group(1), m.group(2)
what if this doesn't match? let's log and continue.

http://codereview.appspot.com/975/diff/1/4#newcode24
Line 24: digest = Digest.gql('WHERE hash = :1', hash).get()
name this digests, and instead of get() do get(100) (see the API I think that's
how you get all matches).

http://codereview.appspot.com/975/diff/1/4#newcode30
Line 30: del_count += 1
else logging.warning ...