PERF: Return RangeIndex from RangeIndex.reindex when possible
Discovered in https://github.com/pandas-dev/pandas/pull/57441
I think something went wrong with git here, feels like this have unrelated changes, right? As of 1a122350fd9acab946099d3a3e990b8a2af9b661, I think the diff against main should be minimal to the changes now. (In 370d20cb0ca46009c439e1dc9d6e805196df5271 I merged upstream incorrectly)