I guess that had a bug number: add it to the changes file.

changes/clear_trackexithost

@@ -1,5 +1,5 @@
   o Minor bugfixes:
     - Fix a bug in the code where we could keep trying to use a
       TrackHostExits-based mapping after we failed to reach the intended
-      destination node.  Bugfix on 0.2.0.20-rc.
+      destination node. Fixes bug 2999. Bugfix on 0.2.0.20-rc.