In MergeTableRegionsProcedure, we issue UnassignProcedures to offline regions to merge. But if we restart master just after MergeTableRegionsProcedure finished these two UnassignProcedure and before it can delete their meta entries. The new master will found these two region is CLOSED but no procedures are attached to them. They will be regard as RIT regions and nobody will clean the RIT state for them later.
A quick way to resolve this stuck situation in the production env is restarting master again, since the meta entries are deleted in MergeTableRegionsProcedure. Here, I offer a fix for this problem.