[Yum] when mediaid is provided yum crash instead of disabling it

[Muayyad AlSadi]

hello,

when we add

[InstallMedia]
name=Fedora 13
mediaid=1273712675.937554
metadata_expire=-1
gpgcheck=0
cost=500
enabled=1

we got

Error: Cannot retrieve repository metadata (repomd.xml) for
repository: InstallMedia. Please verify its path and try again


I remember that if mediagrabber is not specified such repo should be
disabled automatically
why do we start to get this error ?