policy: postinst abort-remove without in-favour not allowed by maintscript templates

[Justin Pryzby <justinpryzby@users.sourceforge.net>]

clone 372145 -1
reassign -1 debian-policy
severity -1 normal
thanks

I've been reading more thorougly about the dpkg maintainer script
interface.  I noticed that the neither the dpkg maintscript comments
nor your maintscript templates allow for the postinst "abort-remove"
case which is called with only a single parameter (instead of $2 =
"in-favour").  I've filed #372145 against dpkg to fix the comments.
The template files used should be updated too, especially for the
policy package, since they are a good reference; I'd like to patch
dh_make shortly to use some combination of your code and dpkg
comments.