Fedora 21 Alpha blocker tracker bug, as per http://fedoraproject.org/wiki/BugZappers/HouseKeeping/Trackers
To propose a bug as blocking the Fedora 21 Alpha release, mark it as blocking this bug (or use the webapp: https://qa.fedoraproject.org/blockerbugs/propose_bug ). It will be reviewed per https://fedoraproject.org/wiki/QA:SOP_blocker_bug_process . To propose a bug as a 'freeze exception' for the Alpha release - allowing a fix to go through the Alpha freeze, but not blocking the release - mark it as blocking the bug F20AlphaFreezeException . See https://fedoraproject.org/wiki/QA:SOP_freeze_exception_bug_process for the freeze exception process.
F21 has been shipped.