files in /usr/share during package build

[Hleb Valoshka <375gnu@gmail.com>]

Hi team.

Some packages have data which according to policy should go
/usr/share/<pkgname>/. This data is usually accessed as
'../../../<datadir>', if I change this path to
'/usr/share/<pkgname>/<datadir>', then tests can't access data. If I
change them to '../../../../../share/<pkgname>/<datadir>', then I use
Gem2Deb::Rake::TestTask.new then tests can access data but only if
tests use test-unit/minitest, not rspec.

RSpec::Core::RakeTask.new runs tests in build directory, so they can't
access data copied to debian/.../usr/share/...

I have no idea how to make rspec tests working during package build,
please suggest something.