The scripts alread have "#!/bin/bash" as the first line, I noticed them too a while back the best fix (and only real option) is to link /bin/sh to bash. Somehow the ubuntu developers feel they should save a few seconds/bytes at the expense of everyone else, so they justify this using some lame and dusty posix standard (that nobody really cares about anyway) as an excuse. Not to mention the lies and nonsense about it on some dash propagande page in their wiki
ln -sf bash /bin/sh
I think there is another way to do this using the package management, this link could be "restored" during an upgrade. I'll cross that bridge when it happens, my fix wil likely be to get rid of this dash abomination altogether on my system.