fix: resolve flaky tests by using delay=-1 for immediate job scheduling

The tests test_sigint, test_sigterm, test_suppress_dj_errors, and
test_populate_exclude_error_and_ignore_jobs were flaky due to a race
condition: jobs created with scheduled_time=NOW(3) might not pass the
scheduled_time <= NOW(3) check if checked in the same millisecond.

Fix by using delay=-1 in auto-refresh during populate(), ensuring jobs
are scheduled 1 second in the past and immediately schedulable.

Also update test_populate_exclude_error_and_ignore_jobs to use delay=-1
in its explicit refresh() call.

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: dimitri-yatsenko

src/datajoint/autopopulate.py

@@ -485,7 +485,9 @@ def handler(signum, frame):
             if refresh is None:
                 refresh = config.jobs.auto_refresh
             if refresh:
-                self.jobs.refresh(*restrictions, priority=priority)
+                # Use delay=-1 to ensure jobs are immediately schedulable
+                # (avoids race condition with scheduled_time <= NOW(3) check)
+                self.jobs.refresh(*restrictions, priority=priority, delay=-1)
 
             # Fetch pending jobs ordered by priority (use NOW(3) to match CURRENT_TIMESTAMP(3) precision)
             pending_query = self.jobs.pending & "scheduled_time <= NOW(3)"

tests/integration/test_autopopulate.py

@@ -66,7 +66,8 @@ def test_populate_exclude_error_and_ignore_jobs(clean_autopopulate, subject, exp
     assert not experiment, "table already filled?"
 
     # Refresh jobs to create pending entries
-    experiment.jobs.refresh()
+    # Use delay=-1 to ensure jobs are immediately schedulable (avoids race condition with NOW(3))
+    experiment.jobs.refresh(delay=-1)
 
     keys = experiment.jobs.pending.keys(limit=2)
     for idx, key in enumerate(keys):