product_id is being set to 0 instead of NULL.
This is also the case when directly removing the product from the recipeset.
*** Bug 1043429 has been marked as a duplicate of this bug. ***
Judging by the git history this is not a regression, I believe this case has never worked since the feature was added in Beaker 0.5.63.
http://gerrit.beaker-project.org/2623
This change is included in the Beaker 0.15.3 maintenance release: http://beaker-project.org/docs/whats-new/release-0.15.html#beaker-0-15-3