Wrong clef at start of system

Ubuntu Studio 14.04, GIT commit: cf1da9f

First reported in http://musescore.org/en/node/28821#comment-116216. It's a bit tricky to reproduce as the specifics are quite sensitive to the exact order in which you do things, but it's not at all hard to get the clef at the beginning of the second system to be wrong. I am hoping this will turn out to be different manifestations of the same bug.

#1:

1) new score for flute, 32 measures
2) fill first six measures with quarter notes ("C" works fine)
3) add line break after fourth measure
4) click first note of fourth measure
5) double click alto clef in palette
6) select clef you just added
7) delete

Result: clef is deleted from measure 4, but remains at beginning of next system
Expected result: second system reverts to treble clef

#2)

1) new score for flute, 32 measures
2) fill first six measures with quarter notes ("C" works fine)
3) add line break after fourth measure
4) click first note of second measure
5) double click bass clef in palette
6) click first note of third measure
7) double click treble clef in palette

Result: bass clef remains at start of second system
Expected result: second system changes to treble clef

#3

1) new score for flute, 32 measure, set page size to Letter
2) fill first twelve measures with quarter notes
3) drag (don't use click / double-click) alto clef to first note of measure 9 (last measure of first system)

Result: measure 9 moves to next system, but no clef appears; instead the clef appears hovering over the third system