The bad thing with fixing build failures with dash is that there are still a lot of open bugs. (Remember, the 0-day NMU policy applies to those, so it’s a good opportunity to improve your NMU karma. And I will sponsor your NMUs if you can’t upload!).
The good thing is that you sometimes run into funny code, like:
pushd docs ; $(MAKE) distclean || true ; popd
Since pushd/popd is a bashism, the Ubuntu patch changed this to:
cd docs ; $(MAKE) distclean || true ; cd $(CURDIR)
Which works, but is … interesting? :-)