Fix lost build row updates.

Sometimes poll_stale_build() has to insert a build row with missing
data, assuming it would be updated later in process_new_build_status().
That didn't actually happen, so we could finish up with some rows that
had NULL columns.

It would be nicer if those columns were NOT NULL and we didn't have to
insert a sort of "dummy" row, but that's needed for serialisation.  We
could lock something else instead...

Author: macdice

cfbot_cirrus.py

@@ -432,18 +432,17 @@ def process_new_build_status(
         logging.info(
             "build %s %s -> %s [%s]", build_id, old_build_status, build_status, source
         )
-        cursor.execute(
-            """update build
+    else:
+        logging.info("new build %s %s [%s]", build_id, build_status, source)
+    cursor.execute(
+        """update build
                              set status = %s,
                                  commit_id = coalesce(commit_id, %s),
                                  branch_name = coalesce(branch_name, %s),
                                  modified = now()
                            where build_id = %s""",
-            (build_status, commit_id, branch_name, build_id),
-        )
-    else:
-        logging.info("new build %s %s [%s]", build_id, build_status, source)
-        # caller inserted build
+        (build_status, commit_id, branch_name, build_id),
+    )
 
     # maintain the history of status changes
     cursor.execute(