Bug#918620: britney: blocks arch:all packages on non-installability on CI archs

[Niels Thykier <niels@thykier.net>]

Paul Gevers:
> Control: tags -1 patch
> Control: forwarded -1
> https://salsa.debian.org/release-team/britney2/compare/31e32782...c9e8751c
> 
> Hi all
> 
> On 28-11-2019 10:28, Paul Gevers wrote:
>> With the addition of arm64 as a CI architecture, the situation got
>> worse. E.g. https://qa.debian.org/excuses.php?package=q2-demux currently
>> shows:
>> """
>> uninstallable on arch arm64, autopkgtest delayed there
>> Additional info:
>> q2-demux/i386 unsatisfiable Depends: python3-skbio
>> """
>>
>> Indeed, the arch:all package q2-demux depends on python3-skbio, which is
>> only available on amd64.
> 
> Ivo and I had a discussion about this at the miniDebCamp @ Brussels. I
> prepared a solution.
> 
> Paul
> 

Looks good to me!  If it passes the relevant tests (props for adding a
test case), then I think we should merge it!

Thanks,
~Niels