Allow nonexistent releases in default_data
Allow nonexistent releases in default_data

Each "repos" data can contain the list of releases.
If not containing releases, TypeError happens on current code.
This patch makes the code allow nonexistent releases instead of
the exception.

Change-Id: I264784bdfbd016cbd0225a0604d03acfe5ecf967

stackforge/stackalytics,openstack/stackalytics,0xf2/stackalytics,openstack/stackalytics,0xf2/stackalytics,0xf2/stackalytics,openstack/stackalytics,stackforge/stackalytics,openstack/stackalytics,0xf2/stackalytics,stackforge/stackalytics