To make sure that I'm not wandering, I made an own experiment, where I put some code in postinst which prints the variables. (I uploaded it to the same PPA.) Please see the result in the attached file.
So, considering that we must distinguish between upgrades and pure configuration, only testing if $2 exists is not sufficient. I still think that the code I proposed does the right thing. ;)
To make sure that I'm not wandering, I made an own experiment, where I put some code in postinst which prints the variables. (I uploaded it to the same PPA.) Please see the result in the attached file.
So, considering that we must distinguish between upgrades and pure configuration, only testing if $2 exists is not sufficient. I still think that the code I proposed does the right thing. ;)