hi everybody

you probably have notice yum broke repos config or/and 
something broke in repos configs or/and in yum
and you get funky urls:

ftp://ftp.scientificlinux.org/linux/scientific/%24slreleasever/x86_64/os/Packages/minicom-2.6.2-5.el7.x86_64.rpm: 
[Errno 14] FTP Error 550 - Server denied you to change to 
the given directory

quick workaround is to use:
/etc/yum/vars/slreleasever # and value in it

I wonder what broke?
regards