We have found out that one of the changes that were planned to be included in the 3.1.2 release has the potential to cause tasty incompatibility with previous 3.1.x releases. This is unacceptable, so we reverted the change and released 3.1.2-RC3.
If you wanted to use the removed improvement - the possibility to use tailrec calls in explicit returns - you don’t need to worry. It will be back in 3.2.
The stable release of 3.1.2 is expected in slightly more than a week.
GitHub release can be found here.