fixup! Serialize background tasks

kolibri_explore_plugin/jobs.py

@@ -107,7 +107,11 @@ def enqueue_next_background_task():
     """Locate the next background task and enqueue it for running"""
 
     # If there's already a job in progress, do nothing. We only want a
-    # single background task running.
+    # single background task running in order to not slow down the user
+    # interface and to leave room in the worker pool for user-triggered
+    # downloads.
+    #
+    # https://github.com/endlessm/kolibri-explore-plugin/pull/762
     in_progress_jobs = BackgroundTask.objects.exclude(job_id="").exclude(
         job_state__in=[State.FAILED, State.CANCELED, State.COMPLETED]
     )