labhub/assign: Support short issue references

... of the form `#12`.

plugins/labhub.py

@@ -256,8 +256,19 @@ def process_full_url(issue_reference):
 
             return m.group(2), m.group(3)[:-1], m.group(4)
 
+        # Short issue reference (e.g. `coala/corobo#12`)
+        def process_short_ref(issue_reference):
+            rgx = r'(.+?)/(.+?)#(\d+)'
+            m = re.fullmatch(rgx, issue_reference, re.IGNORECASE)
+
+            if m is None:
+                return None
+
+            return m.group(1), m.group(2), m.group(3)
+
         issue_processors = [
-            process_full_url
+            process_full_url,
+            process_short_ref
         ]
 
         for issue_processor in issue_processors:

tests/labhub_test.py

@@ -153,6 +153,11 @@ def test_assign_cmd(self):
         testbot.assertCommand(cmd,
                               'Invalid issue.')
 
+        # test short issue reference
+        mock_issue.assignees = tuple()
+        testbot.assertCommand('!assign coala/a#23',
+                              "You've been assigned to the issue")
+
         cmd = '!assign https://github.com/{}/{}/issues/{}'
         # no assignee, not newcomer
         mock_issue.assignees = tuple()