rawhide repodata uses HTTPS to download the metalink file, and later links to referenced repodata and packages contains their hashes, which protects against replacing any of the files. Please add certificate verification to the HTTPS downloads (at least to the metalink download) to close the last opportunity for MITM attacks. (python-urlgrabber 3.1.0 seems to support certificate verification, you can use the system-wide certificate bundle in /etc/pki/tls/certs/ca-bundle.crt ).
This bug appears to have been reported against 'rawhide' during the Fedora 11 development cycle. Changing version to '11'. More information and reason for this action is here: http://fedoraproject.org/wiki/BugZappers/HouseKeeping
urlgrabber in rawhide/f12 does this properly and by default.