Repository-Stored Specs (RSS) can only be scanned from the "root" (or primary) branch of the linked repository. Defaults here include master (Git), default (Hg), or trunk (SVN).
Allow RSS to be scanned from branches as well as the primary.
Some teams may store Bamboo Specs centrally, but have data that cannot be shared between teams. With the current functionality, the data would have to be shared, but with branches, each sub-organization can manage Specs on their own branch.
One possible workaround may be to add one Linked repository per branch with specs definitions.