Move resolving git reference to config validation

Instead of multiple places handling the same thing duplicating the
logic, it's better to do it once upfront. This allows easy caching of
the results.

Additional advantage of this approach is that the config dump will
include resolved URLs. The original reference will still be available in
the copy of the original config.

JIRA: COMPOSE-3065
Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

tests/test_imagebuildphase.py

@@ -549,47 +549,6 @@ class TestImageBuildPhase(PungiTestCase):
         args, kwargs = phase.pool.queue_put.call_args
         self.assertTrue(args[0][1].get('scratch'))
 
-    @mock.patch('pungi.util.resolve_git_url')
-    @mock.patch('pungi.phases.image_build.ThreadPool')
-    def test_image_build_resolve_ksurl(self, ThreadPool, resolve_git_url):
-        compose = DummyCompose(self.topdir, {
-            'image_build': {
-                '^Server$': [
-                    {
-                        'image-build': {
-                            'format': ['docker'],
-                            'name': 'Fedora-Docker-Base',
-                            'target': 'f24',
-                            'version': 'Rawhide',
-                            'ksurl': 'git://git.fedorahosted.org/git/spin-kickstarts.git?#HEAD',
-                            'kickstart': "fedora-docker-base.ks",
-                            'distro': 'Fedora-20',
-                            'disk_size': 3,
-                            'arches': ['x86_64'],
-                            'scratch': True,
-                        }
-                    }
-                ]
-            },
-            'koji_profile': 'koji',
-        })
-
-        self.assertValidConfig(compose.conf)
-
-        resolve_git_url.return_value = 'git://git.fedorahosted.org/git/spin-kickstarts.git?#BEEFCAFE'
-
-        phase = ImageBuildPhase(compose)
-
-        phase.run()
-
-        # assert at least one thread was started
-        self.assertTrue(phase.pool.add.called)
-
-        self.assertTrue(phase.pool.queue_put.called_once)
-        args, kwargs = phase.pool.queue_put.call_args
-        self.assertEqual(args[0][1]['image_conf'].get('image-build', {}).get('ksurl'),
-                         resolve_git_url.return_value)
-
     @mock.patch('pungi.phases.image_build.ThreadPool')
     def test_image_build_optional(self, ThreadPool):
         compose = DummyCompose(self.topdir, {