Importer creates units for branches not specified in the branches list.
The importer should not create units for branches not listed in the branches list.
Steps to reproduce:
1. Create an ostree repository (A) with a feed pointing to a remote repository with several branches. Be sure to specify all of the branches.
2. Sync repo A.
3. Create another repository (B) with the same feed but this time, specify only 1 branch.
4. Sync repo B.
5. Repo B should only contain the branch specified.
Limit the units to only those branches in the branches list.