Adding key signature does not add accidentals to existing notes

Windows 7, GIT commit: b49579d

1) new score flute, C major, 4/4, >2 measures
2) note entry, two measure of quarter note C's
3) drag D major key signature to bar 2?

Expected result: a natural sign appears before the first C
Actual result: no natural sign appears

The C's in that measure play back correctly (as C natural), but without the natural sign, the displayed pitch is wrong. Upon any operation that changes any of the pitches in that measure (eg, clicking the last note hit up arrow), the natural sign appears and all seems OK.