We don't want to take the time to check out all of the source code for
all projects during the documentation build, so add a validation step to
check that the deliverable being modified has the tarball-base value set
properly, if it needs to be overridden from the default.
Change-Id: Id39bdd1e0a9fe771b78a053ba73803c3c095f135
Signed-off-by: Doug Hellmann <doug@doughellmann.com>
