[trunk & 0.9.6.3 Stable] Bar line style not preserved before a courtesy key signature

Steps:
1- Open test.mscz
2- Look at the bar lines between 18 and 19 and between 38 and 39
3- Select first measure
4- Layout > Add More Stretch
5- Look at the bar lines between 18 and 19 and between 38 and 39
6- Edit > Undo
7- Look at the bar lines between 18 and 19 and between 38 and 39

Actual Result:
The style of the bar line has changed (from dashed to single line; from double line to single line).

Expected Result:
After using undo, we should retrieve the original file.
(After saving and reloading, the bar line style was not retrieved as well, i.e. it remains single line.)

OS and MuseScore version:
-Windows XP Professional SP2:
0.9.6.3 Stable
Nightly build r3775
-Fedora 13 kernel 2.6.34.7-63.fc13.i686:
0.9.6.3 Stable (from repo)
-Windows 7 Enterprise N (64-bit):
Nightly build r3775
(0.9.6.3 not checked)

Notes:
The bug is related to the presence of the courtesy key signature.