Tor Browser bundle v3.5 fails to clean up cancelled downloads in Temp folder

1. Run TBB v3.5.3
2. Click on a link to download an archive or any file type not natively handled by the browser
3. Wait for the download to complete
4. Observe that .ext.part file is created containing entire file contents in the system's %temp% folder.
5. In the Open/Save dialog box click Cancel.
6. Observe that the temp-created file is not removed.
7. Close Firefox/TBB.
8. Observe that the temp-created file is not removed.

Firefox 28's Private Mode does not have this bug. I observed this bug in TBB v2.x as well.

Trac:
Username: ericlaw