Actually, your patch doesn't fix bug #172439. The problem is in the postinst script. If /etc/locale.gen exists, bug XXX GENERATED XXX is not present in it, postint won't touch /etc/locale.gen.
But it does fix bug #156386. I posted a patch there yesterday, but yours is nicer :-) I think this whole locale.postinst magic is quite confusing and should be removed. -- Peter Nagy, GPG: E54BDFC8/ D90B 981D 50EE F6B1 FD47 5156 5997 047E E54B DFC8
