Pasting grace note on existing one makes it disappear

1. Open score .
2. Select the grace note only.
3. Copy.
4. Click the grace note.
5. Paste.

Expected result: The grace note is replaced with what was copied.
Actual result: The grace note disappears.

Discussion: It's the same actual result if you paste a normal note on the grace note - I'm unsure what the expected result should be.

Using MuseScore 2.0 Nightly Build (5086) - Mac 10.6.8.