When using the following command: fedup --network 21 --instrepo=http://dl.fedoraproject.org/pub/fedora/linux/releases/test/21-Alpha/Workstation/x86_64/os/ to try to upgrade from fedora20 to fedora21-alpha the reboot to upgrade loops endlessly between failures in systemd-journald-dev-log.socket and systemd-udevd.service. \
I marked this as urgent because it would seem to be blocking the release.
I meant to add I tried this on 2 different systems one with an AMD64 processor and another with an Intel 64-bit processor, so this is not processor or hardware specific.
*** This bug has been marked as a duplicate of bug 1099299 ***