v3.15.0a2
gh-85524: Raise "UnsupportedOperation" on FileIO.readall (#141214)
gh-141376: Fix exported symbols (GH-141377)
gh-141311: Avoid assertion in BytesIO.readinto() (GH-141333)
gh-141314: Fix TextIOWrapper.tell() assertion failure with standalone carriage return (GH-141331)