Proper validation of repository link

We need to skip most of the validation if link is invalid (we can not
validate file matches and most of other parameters).

Fixes #532.
Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/trans/models/subproject.py

@@ -796,6 +796,7 @@ class SubProject(models.Model, PercentMixin, URLMixin, PathMixin):
         '''
         Validates repository link.
         '''
+        validate_repo(self.repo)
         if self.push != '':
             raise ValidationError(
                 _('Push URL is not used when repository is linked!')