On 9/28/21 4:56 PM, Stephen Colebourne via tz wrote:
What I discovered was that the primary damage to Joda-Time would have come from the commit that move the Links from the main files to backward (2a18a625a0171e5c54249a54179eda3409b1b838).
Thank you for reporting the problem. The commit you mention is independent of the alike-since-1970 merge and so it's not that important. I reverted it by installing the attached patch into the tzdb development repository. If you'll compare the resulting 'backward' file to what you derived in your copy, you should find only a couple of minor differences, which I'm also attaching to this email separately, as a convenience. I hope this serves as an effective merge of the two versions. It sounds like we should release tzdb 2021c shortly, since this is a significant problem downstream.
Previous merges have not (I believe) moved the resulting link into backward.
Previous merges were not consistent. Sometimes they moved the resulting Link into 'backward' (e.g., America/Coral_Harbour, Europe/Belfast), but often (as you noticed) they did not. Although (as others have noted in recent emails to this list) it would be nice to fix Link inconsistencies, that's not urgent and right now the priority is to address the 2021b compatibility issue that you mentioned.