Bars overlap when shrunk

Shrink a bar, and the bars overlap and the display becomes unreadable.
This shrinking feature usually works well, except on this document that I have attached (I have no idea
what's so special about it....)

Steps to reproduce: (this is on 0.9.6 beta2 r2811, Windows XP SP2)

- open the attached file
- select the 3rd bar (the one with the D7 chord above it)
- use the { shortcut to shrink the bar

Problem: The bars become all messed up because they overlap each other.
See "before" and "after" screenshots.

Desired behavior : the selected bar should only shrink slightly, and if that creates enough room to add
an extra bar on the line, then by all means add it, but if there's no room, don't add it; in all cases notes
from one bar should not appear in another bar.

Notes:
1) same thing happens with the 1st bar
2) same thing happens with the 2nd bar but you have to use the shortcut 4 or 5 times
3) this was also present in 0.9.5
4) if I save the doc and reopen it, its reopens with the bars overlapping
5) undoing or stretching correctly restores previous state
6) if you press { a lot of times, the bar shrinks for a while, but then starts expanding- this behavior seems counter-intuitive and wrong.

This bug was discussed on the forum here
where Lasconic said the attached file crashed the current trunk (don't know what version that was, on March 7, 2010)