turku-storage not logging attic failures to web UI

I had a backup source that was failing to attic archive correctly but the error was not showing up in the turku admin web UI. I only discovered this because a previous rsync failure was logged, but became suspicious when no recent success or failures were logged.

Digging in the turku-storage.log on the backup source's storage unit I saw the failure (with UUIDs out):
[2016-11-17 20:41:29,054 <UUID> 29766] INFO: Sources to back up: etc
[2016-11-17 20:41:29,073 <UUID> 29766] INFO: Begin: maqui etc
[2016-11-17 20:41:29,078 <UUID> 29766] DEBUG: Running: ['rsync', '--archive', '--compress', '--numeric-ids', '--delete', '--delete-excluded', '--verbose', '--inplace', u'rsync://<STORAGE_UUID>@127.0.0.1:60246/etc/', u'/media/turku_storage_1-turku_storage/<UUID>/etc/']
[2016-11-17 20:41:29,079 <UUID> 29766] DEBUG: (Command output is in /tmp/tmpY7kDML until written here at the end)
[2016-11-17 20:41:30,281 <UUID> 29766] DEBUG: receiving incremental file list
[2016-11-17 20:41:30,281 <UUID> 29766] DEBUG:
[2016-11-17 20:41:30,281 <UUID> 29766] DEBUG: sent 310 bytes received 100,956 bytes 67,510.67 bytes/sec
[2016-11-17 20:41:30,281 <UUID> 29766] DEBUG: total size is 7,645,365 speedup is 75.50
[2016-11-17 20:41:30,281 <UUID> 29766] DEBUG: Return code: 0
[2016-11-17 20:41:30,282 <UUID> 29766] DEBUG: Running: ['attic', 'create', '--numeric-owner', u'/media/turku_storage_1-turku_storage/<UUID>/etc.attic::2016-11-17T20:41:30.282075', '.']
[2016-11-17 20:41:30,282 <UUID> 29766] DEBUG: (Command output is in /tmp/tmpqVknl5 until written here at the end)
[2016-11-17 20:41:30,641 <UUID> 29766] DEBUG: attic: Error: Data integrity error
[2016-11-17 20:41:30,642 <UUID> 29766] DEBUG: Return code: 1
[2016-11-17 20:41:30,825 <UUID> 29766] ERROR:
CalledProcessError: Command '['attic', 'list', u'/media/turku_storage_1-turku_storage/<UUID>/etc.attic']' returned non-zero exit status 1

After creating a backup copy of the archive and then using "attic check --repair" on it, the next backup succeeded and logged correctly.