could you confirm this,
swap partition show curious display in /dev/.udev/db/block@sdc@sdc1
where sdc1 needs to reflect your hardware configuration.
Ananconda should have zap the first sector of partition, like
dd if=/dev/zero of=/dev/MY_PARTITION bs=512 count=1 # for me MY_PARTITION is sdc1
before using mkswap utility.
Problen shown, during boot udev may complained about alredy added label because of the line
S:disk/by-label/ if it found a label containing non-ascii characters, this label is displayed on line
you may produce the line
swapoff, reformat partition for fat, mkswap /dev/sdc1, swapon /dev/sdc1
looks at that line again.