Bug#723974: grass FTBFS on buildds because it build depends on versioned virtual package

[Paul Gevers]

Package: grass
Version: 6.4.3-1
Severity: serious
Justification: fails to build from source (but built successfully in the past)

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In the latest upload of grass, the build dependency for libtiff has been changed to
libtiff-dev (>> 4.0.3-1~) | libtiff5-dev
However, build deamons only consider the first build dependency, and that is invalid
as libtiff-dev is a virtual package. So now grass is not building [1].

Policy 7.5 says this:
If a relationship field has a version number attached, only real packages will be
considered to see whether the relationship is satisfied (or the prohibition violated,
for a conflict or breakage). In other words, if a version number is specified, this is
a request to ignore all Provides for that package name and consider only real
packages. The package manager will assume that a package providing that virtual
package is not of the "right" version. A Provides field may not contain version
numbers, and the version number of the concrete package which provides a particular
virtual package will not be considered when considering a dependency on or conflict
with the virtual package name.

[1] https://buildd.debian.org/status/package.php?p=grass

Thanks for considering.

- -- System Information:
Debian Release: 7.1
  APT prefers stable
  APT policy: (500, 'stable'), (99, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 3.2.0-4-amd64 (SMP w/1 CPU core)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

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