Corruption on note entry after clearing measure

I've been seeing variations on this a while now, but I finally realized the (simple) steps to reproduce:

1) open attached score
2) click an empty spot in measure 2 to select it
3) hit Delete (Fn-Delete on Mac, I guess) to clear contents
4) Press N to enter Note Input mode *without first clicking anywhere*
5) Press C to enter a C

Expected result: a C quarter note is placed at the beginning of the measure, rest of measure filled with quarter rest & half rest, original full measure rest gone
Actual result: a half rest is inserted in the middle of the measure, with the original full measure rest also still present

At this point the score is semi-corrupt. Selecting the measure and hitting Delete again does seem to fix it. Undo is not your friend here, though.

The problem seems to occur right at step 4 - you can tell by the cursor location that trouble is brewing before you try to enter the note at step 5.

I'm calling it critical due to the corruption, even though it's possible to recover if you act wisely and soon enough.

Windows 7, GIT commit: eee9f5f