Fix upload to not have a redundant directory

The existing config creates a bad URL:
http://tarballs.openstack.org/ironic-python-agent/coreos/
ipa-coreos.tar.gz/ipa-coreos.tar.gz -- this is an attempt to prevent
duplicating the ipa-coreos.tar.gz.

Change-Id: I7f17874aaa74e83a46cd821ac409cf4e045e128d