[Python-modules-team] Bug#831336: python-cffi: Versioned Provides not supported by buildds

[Bas Couwenberg]

Source: python-cffi
Version: 1.6.0-1
Severity: serious
Justification: makes the package in question unusable or mostly so
Control: block 830966 by -1
Control: affects -1 python-cryptography vtk6

Dear Maintainer,

The versioned provides in enabled in 1.6.0-1 are preventing the buildds
from rebuilding vtk6 for the ongoing gdal transition (#830966), the
python-cryptography dependencies on the python-cffi-backend virtual
packages cannot be installed:

 python-cffi-backend-api-min (<= 9729),
 python-cffi-backend-api-max (>= 9729)

The buildd status page for vtk6 reports:

 vtk6 build-depends on:
 - amd64:python-twisted
 amd64:python-twisted depends on:
 - amd64:python-twisted-core (>= 16.2.0-1)
 amd64:python-twisted-core depends on:
 - amd64:python-openssl
 amd64:python-openssl depends on:
 - amd64:python-cryptography (>= 1.3)
 amd64:python-cryptography depends on missing:
 - amd64:python-cffi-backend-api-min (<= 9729)

Please disable the versioned provides until it's fully supported in all
Debian infrastructure, its support in britney is not sufficient.

python-cryptography and possibly other affected reverse dependencies of
python-cffi will need to be rebuilt after this issue is fixed to correct
their dependecies automatically set via ${python:Depends}.

Kind Regards,

Bas