Bug#898049: libdune-grid-dev: Differing versions break multi-arch support

[Ansgar Burchardt]

Hi,

Francois Gouget writes:
> This concerns Debian Testing and Unstable:
>
> * For the alpha, amd64, arm64, mips64el and ppc64el architectures only 
>   version 2.6.0-1+b1 is available.
>
> * For the armel, armhf, i386, mipsel and x32 architectures only
>   version 2.6.0-1 is available.

Yes, some builds failed.  I tried reproducing the build failures, but
on armhf the compiler on the porterbox crashed (internal compiler
error) and on i386 the build dependencies were not installable when I
looked.

On x32 the build dependencies are not installable (missing python-vtk6
rebuild against newer OpenMPI).

>  But libdune-grid-dev says that it breaks any version that's different. For 
>   instance:
>   Breaks: libdune-grid-dev (!= 2.6.0-1+b1)
>
> Thus, because the amd64 and i386 architectures (for instance) are not available in
> the same version, they are not coinstallable, thus breaking multi-arch support.
>
> Presumably at some point a new version will be available for all architectures, 
> which will fix this. But this illustrates that:
>
> * Either the Breaks: statement should be revised. Maybe it should target releases 
>   older than a specific version or could be removed.

Not possible.  There is no `Breaks:` in the package, but an implicit
`Breaks:` is added for multi-arch packages.

> * Or one should not just rebuild this package for a subset of the architectures to
>   avoid breaking multi-arch.

If I don't find time to look at the errors or still get compiler errors,
I'll probably ask for removal of the binary packages on the failing
architectures.

Ansgar