Better webhook handling, new URL generation.

1.  Usually we have enough information in the webhook payload, so we can
avoid a lot of API calls (which are counted and limited).  In some cases
we can't or they seem to arrive out of order (by a primitive status
ordering rule), so we fall back to polling in that case.  Time will tell
how well this works in practice...  The code for both cases is unified.

2.  There are now also URL properties for builds and tasks, which will
be pushed to the CF app so that it can create clickable links.
They aren't directly taken from the Github API's html_url fields,
because I wanted to include the run_attempt explicitly in the build URL.
The links it makes for builds always take you to the latest run attempt,
which might be confusing in some rare cases...

Author: macdice

cfbot_commitfest.py

@@ -177,22 +177,32 @@ def make_branch_status_message(conn, branch_id=None, build_id=None, commit_id=No
 def make_task_status_message(conn, task_id):
     cursor = conn.cursor()
     cursor.execute(
-        """SELECT build_id, build.commit_id, task.task_name, task.position, task.status, task.created, task.modified
+        """SELECT build_id, build.commit_id, task.task_name, task.position, task.status, task.html_url, build.html_url, task.created, task.modified
                       FROM task
                       JOIN build USING (build_id)
                      WHERE task.task_id = %s""",
         (task_id,),
     )
-    build_id, commit_id, task_name, position, status, created, modified = (
-        cursor.fetchone()
-    )
+    (
+        build_id,
+        commit_id,
+        task_name,
+        position,
+        status,
+        task_url,
+        build_url,
+        created,
+        modified,
+    ) = cursor.fetchone()
     message = {
         "build_id": build_id,
         "task_id": task_id,
         "commit_id": commit_id,
         "task_name": task_name,
         "position": position,
         "status": status,
+        "task_url": task_url,
+        "build_url": build_url,
         "created": created.isoformat(),
         "modified": modified.isoformat(),
     }