Oops, you're right. I had failed to notice when reading the code that the second transaction takes an AccessExclusiveLock on the target partition. Reverted back to how this was in v3.
Yeah, maybe the link is unnecessary in the test comment, so removed. Though, I do occasionally see one of those in the test files (try `git grep https src/test`).
Thanks! I don't see problems anymore. The patch is RFC now.