Bug#560406: lintian: warn against use of debconf TITLE command with fixed text

[Frans Pop <elendil@planet.nl>]

Package: lintian
Severity: wishlist
X-Debbugs-CC: debconf@packages.debian.org

Some packages use the command 'db_title' in maintainer scripts to set the 
title for debconf dialogs to a fixed string. Disadvantage is that this 
does not allow the string to be translated.

Because of that the command 'db_settitle' (which takes the title form a 
debconf template) is normally to be preferred.

Please add a warning against setting the dialog title to a fixed string 
using db_title.

A regular expression for that could be:
    db_title[[:space:]]+["']?[^\$]
(One of the quotes may need escaping.)

The explanation could read as follows:
   Using db_title to set the title of a debconf dialog does not allow for
   it to be translated; consider using db_settitle instead.
   See debconf-devel(7) for additional information.

For examples of packages currently getting it "wrong" see:
#560314, #560316, #560318, #560319

There will be false positives as some titles being set this way may not 
need translation (example in #560315).

The test will miss cases where titles are set from a variable containing an 
untranslated string, but those should be extremely rare.

Cheers,
FJP