running cache:clear from the windows command line often fails to perform the rename of the temp folder.

This is due to a php bug:
http://www.php.net/manual/en/function.rename.php#102274

And the issue as it pertains to Symfony is discussed here:
https://groups.google.com/forum/?fromgroups=#!topic/symfony2/9NFunxsDTnQ

The workaround is simply adding a sleep(1) call between the rename() calls.