Versioned provides in wheezy-backports

[Alexander Wirt <formorer@debian.org>]

Hi,

python-cffi-backend has a versioned provides, those provides are not
supported in wheezy and lead to a nasty warning in apt:
W: Ignoring Provides line with DepCompareOp for package python-cffi-backend-api-max
W: Ignoring Provides line with DepCompareOp for package python-cffi-backend-api-min
... and several others.

Please fix this as soon as possible.

Thanks
Alex