Call admint_project_builds to dispatch immediately if possible

Author: humitos

readthedocs/core/utils/__init__.py

@@ -246,9 +246,11 @@ def trigger_build(project, version=None, commit=None, from_webhook=False):
 
     # Feature-flag dispatch: isolated-builders path vs legacy Celery path.
     if project.has_feature(Feature.USE_ISOLATED_BUILDER):
-        # The build stays in ``triggered``; the periodic ``admit_queued_builds``
-        # task enforces concurrency and dispatches it to the isolated-builders
-        # fleet when a slot is free. See :func:`admit_project_builds`.
+        # The build stays in ``triggered``; we call `admit_project_builds` to dispatch immediately
+        # if there is a slot free. Otherwise, it waits for a later pass of the periodic ``admit_queued_builds``
+        # task that enforces concurrency and dispatches it to the isolated-builders
+        # fleet when a slot is free.
+        admit_project_builds(project)
         return None, build
 
     task = update_docs_task.apply_async()