MIDI overdub + autopunch + preroll/count-in: extra notes recorded when notes played before selection start

When recording MIDI in overdub mode using one of the autopunch modes and preroll/count-in, if notes are played before the record cursor reaches the selection/item, duplicates of those notes are added covering the whole selection/item.

See the following licecap:


Settings:
- record input: MIDI/overdub
- metronome count-in 1 measure
- record mode: autopunch time selection

Actions:
- playback cursor at start of time selection
- start recording
- before cursor reaches selection start, press and hold a note
- release note after cursor has moved inside of time selection

Results:
- at first the item looks ok: a note starting at the beginning of the item, lasting until the note was released
- when opening the MIDI editor it shows that there is an extra note (same key) that covers the whole item

Expected results:
- only the notes I have entered should be recorded!

Tested with fresh (portable) installs of Reaper 4.21 x86 and x64 on Windows 7 Home Premium x64 and Windows 7 Professional x64.


This is a massive bug when recording MIDI and makes overdub MIDI recording unreliable to unusable, hence priority 2.