DM-5822 as a release blocker.
Although it hasn't been solved yet I don't think we should block on it for the following reasons:
0. This bug was likely also part of the previous release and didn't bite anyone.
1. Users will only be bit by it if they build without optimisation.
2. If the bug is triggered for a particular system I am reasonably confident it will show up in the unit test.
When a solution is found I plan to backport it to the release. I do however suggest to add a note to the release informing users of this open issue and advising them to check their SCONSFLAGS if the unit test for convolve fails in afw.