Hi,
of course you can "fix" this issue by going back to the state that brought us these bashisms in the first place. The correct way to do this, in Debian and derivates, is
dpkg-reconfigure dash
so the system actually knows and stores your preference for future updates/upgrades.
There are situations where it makes sense to do this (specifically development machines with vast build environments like OpenEmbedded where trying to fix every bashism is akin to fighting windmills), but on servers where everything works according to plan except for a single script in the backup agent, I prefer to fix the latter (and even more, have it fixed by HP for the future). ISTR that 8.x now claims "official Debian 7.x DA support", which (given the DA worked correctly apart from some cosmetics like said bashism and complaints that Kernel 3.x could not possibly be Linux) may mean just that - being able to deal properly with any SysV/POSIX compatible Bourne shell playing the system shell role.
HTH,
Andre.