More repos in the get_external_repo returns and error

Fixes: https://pagure.io/koji/issue/3033

hub/kojihub.py

@@ -3759,8 +3759,12 @@ def get_external_repo(info, strict=False, event=None):
     :returns: a map containing the id, name, and url of the repository.
     """
     repos = get_external_repos(info, event=event)
-    if repos:
+    if len(repos) == 1:
         return repos[0]
+    elif len(repos) > 1:
+        # a very defective situation which should never occur
+        # (name/id should be exact identification)
+        raise koji.GenericError('More than one repo in the result.')
     else:
         if strict:
             raise koji.GenericError('No such repo: %s' % info)

tests/test_hub/test_get_external_repo.py

@@ -12,9 +12,41 @@ class TestGetExternalRepo(unittest.TestCase):
         self.get_external_repos = mock.patch('kojihub.get_external_repos').start()
         self.exports = kojihub.RootExports()
 
-    def test_non_exist_repo(self):
+    def test_non_exist_repo_with_strict(self):
         repo = 'test-repo'
         self.get_external_repos.return_value = []
         with self.assertRaises(koji.GenericError) as cm:
             self.exports.getExternalRepo(repo, strict=True)
         self.assertEqual("No such repo: %s" % repo, str(cm.exception))
+
+    def test_non_exist_repo_without_strict(self):
+        repo = 'test-repo'
+        self.get_external_repos.return_value = []
+        rv = self.exports.getExternalRepo(repo, strict=False)
+        self.assertEqual(None, rv)
+
+    def test_valid(self):
+        repo = 'test-repo'
+        repo_info = [
+            {'id': 1,
+             'name': 'build-external-repo-1',
+             'url': 'https://path/to/ext/repo1'},
+        ]
+        self.get_external_repos.return_value = repo_info
+        rv = self.exports.getExternalRepo(repo, strict=True)
+        self.assertEqual(repo_info[0], rv)
+
+    def test_more_repos(self):
+        repo = 'test-repo'
+        repo_info = [
+            {'id': 1,
+             'name': 'build-external-repo-1',
+             'url': 'https://path/to/ext/repo1'},
+            {'id': 2,
+             'name': 'build-external-repo-1',
+             'url': 'https://path/to/ext/repo2'}
+        ]
+        self.get_external_repos.return_value = repo_info
+        with self.assertRaises(koji.GenericError) as cm:
+            self.exports.getExternalRepo(repo, strict=False)
+        self.assertEqual("More than one repo in the result.", str(cm.exception))