storage:util:upgrade: make yaml import optional (unless it isn't)
authorW. Trevor King <wking@tremily.us>
Fri, 26 Oct 2012 17:18:21 +0000 (13:18 -0400)
committerW. Trevor King <wking@tremily.us>
Fri, 26 Oct 2012 17:18:24 +0000 (13:18 -0400)
commit7df9852ddf77304dde98217c71910723602dbde1
tree35b041e780ab6f23d338a2b6d79a160493b6afb8
parent1f771c68eec0cb191bd7d82f0f08134850a88e62
storage:util:upgrade: make yaml import optional (unless it isn't)

Importing `yaml` may fail (if the user doesn't have PyYAML installed),
but don't die until we need to use it.  This way users without the old
YAML formats on disk can run BE without installing PyYAML.
libbe/storage/util/upgrade.py