docs: update Changelog.

docs/changelog.rst

@@ -251,10 +251,14 @@ Fixes
   trigger early finalization of Cython-based extension modules, leading to
   segmentation faults.
 
-* `dc1d4251 <https://github.com/dw/mitogen/commit/dc1d4251 >`_: the
+* `dc1d4251 <https://github.com/dw/mitogen/commit/dc1d4251>`_: the
   ``synchronize`` module could fail with the Docker transport due to a missing
   attribute.
 
+* `599da068 <https://github.com/dw/mitogen/commit/599da068>`_: fix a race
+  when starting async tasks, where it was possible for the controller to
+  observe no status file on disk before the task had a chance to write one.
+
 
 Core Library
 ~~~~~~~~~~~~