I’m sorry that PR did not get finished and merged. We cannot, however—for obvious reasons—merge PRs that don’t pass CI. There was an announced window for testing for the 0.6.4 release which would have been the time to make some noise about the PR and get it into mergeable state.
Making PRs to master and back-porting them is not written in stone but is the way things are generally done for good reason: we don’t want people making fixes on old release branches which are then lost because they are never forward-ported to master; so instead you are asked to make fixes on master if they are still relevant there—which this one seems to be—and we will back-port them for you. In this case it seems unclear that the fix works cleanly on either master or 0.6. While I understand and sympathize with your frustration, I can’t see what could be done without a PR that works and passes CI, if not on master than at least on the
release-0.6 branch. If you want to make a new PR against the
release-0.6 branch and it passes CI there, that helps move things forward since it indicates that the failure is due to some difference since 0.6.