2011-01-19 18:13 AEST by Arthur Barrett - Customer complains that if they checkout a branch that does not exist no 
warning is given.

This is partly due to branches existing in each file - so every file must be 
read to determine if a branch exists or not (or by use of val_tags if 
enabled), and partly for historical reasons.

In a future release I've speculated I could have a SQLite DB used by 
CVSManager to store things like repo revision numbers, perhaps this could be 
used to store val_tags and have a reliable source for branch names?