Bug#891555: Detect and warn about debhelper >= 11 instead of 11~ b-d

[Niels Thykier <niels@thykier.net>]

Thomas Goirand:
> [...]
> 
> And then debhelper 12 is released, people start to use it, and guess
> what happens... :)
> 

I am prototyping an alternative in debhelper that may make this issue
obsolete.  At the moment (since 11.1.5) you can use:

 Build-Depends: debhelper-compat (= 11)

as a replacement for:

 Build-Depends: debhelper (>= 11~)
 and d/compat set to 11.

Note the lack of "~" in the debhelper-compat version.


It spews out tons of warnings as it is still experimental.  Nonetheless,
feedback appreciated.

Thanks,
~Niels