Small conceptual simplification in new_run().

server/fishtest/rundb.py

@@ -501,6 +501,7 @@ def new_run(
         if tc_base:
             tc_base = float(tc_base.group(1))
         new_run = {
+            "_id": ObjectId(),
             "version": RUN_VERSION,
             "args": run_args,
             "start_time": start_time,
@@ -566,9 +567,9 @@ def new_run(
             print(message, flush=True)
             raise Exception(message)
 
-        # We cannot use self.buffer since new_run does not have an id yet.
-        run_id = str(self.runs.insert_one(new_run).inserted_id)
+        self.buffer(new_run, True)
 
+        run_id = new_run["_id"]
         with self.unfinished_runs_lock:
             self.unfinished_runs.add(run_id)
 

server/fishtest/schemas.py

@@ -640,11 +640,11 @@ def flags_must_match(run):
 # about non-validation of runs created with the prior
 # schema.
 
-RUN_VERSION = 4
+RUN_VERSION = 5
 
 runs_schema = intersect(
     {
-        "_id?": ObjectId,
+        "_id": ObjectId,
         "version": uint,
         "start_time": datetime_utc,
         "last_updated": datetime_utc,