[storages] Try to download suffixed keys in precommit events

Since the unsuffixed key is saved in database, a precommit event
fetching an edited attribute doesn't download the new value.
4 jobs for topic/default/callback-precommit in 1 minute and 33 seconds (queued for 24 seconds)
Status Name Job ID Coverage
  Test
passed check_manifest #133031

00:00:19

passed flake8 #133032

00:00:19

passed py27 #133033

00:01:30

passed py3 #133034

00:01:31