- The test on concretization of anonymous dependencies
  has been fixed by raising the expected exception.
- The test on compiler bootstrap has been fixed by
  updating the version of GCC used in the test.
  Since gcc@2.0 does not support targets later than
  x86_64, the new concretizer was looking for a
  non-existing spec, i.e. it was correctly trying
  to retrieve 'gcc target=x86_64' instead of
  'gcc target=core2'.
- The test on gitlab CI needed an update of the target