Call raise_for_status on hg.mozilla.org json-automationrelevance resp…

…onse (#419)

Makes more sense to get an http exception rather than a json decode error.

src/taskgraph/files_changed.py

@@ -49,6 +49,7 @@ def _get_changed_files_json_automationrelevance(head_repository_url, head_rev):
 
     def get_automationrelevance():
         response = requests.get(url, timeout=30)
+        response.raise_for_status()
         return response.json()
 
     contents = retry(get_automationrelevance, attempts=10, sleeptime=10)

test/test_files_changed.py

@@ -36,6 +36,9 @@ def json(self):
         ) as f:
             return json.load(f)
 
+    def raise_for_status(self):
+        pass
+
 
 class TestGetChangedFiles(unittest.TestCase):
     def setUp(self):