xul-ext-firebug: package stops working when Iceweasel 3.5.19 installed

[Jonathan Nieder]

Mike Hommey wrote:

> There are too many addons and too many incompatibilities with old
> versions of them for iceweasel to introduce Breaks for that.

Got it, thanks.

I see that extensions in unstable have something like "Breaks:
iceweasel (>= 10.0~a1+)" (odd choice, that --- a versioned Depends
would seem more natural) so the same problem won't happen again in
wheezy -> wheezy+1 upgrades.