The independent series has to be treated as a special case because it
does not appear in the sequence of normal series.
Not everything in the deliverables directory is actually a series
name, so we need to use the series status data to get the list of
valid names.
Change-Id: Iea9ce55bf3c99afc7bcdd74cc0b7eb523c0a922d
Signed-off-by: Doug Hellmann <doug@doughellmann.com>