centos ships a /etc/yum.conf with "distroverpkg=centos-release"

This causes a problem if you're trying to bootstrap a Fedora environment with something like

 $ rpm --root=$PATH_TO_ROOT --initdb 
 $ rpm --root=$PATH_TO_ROOT -i fedora-release*.rpm
 $ yum --installroot=$PATH_TO_ROOT -y install yum

because yum tries to query for "centos-release" package within "--installroot" (which doesn't exist, only fedora-release was installed).

So once you see this, the seemingly obvious thing to do is to use "--setopt=distroverpkg=fedora-release" to this command to get it working (because it was set in /etc/yum.conf)

In [1] distroverpkg is set after reading the configuration file but before any of the main options are read, so setting via --setopt on the command line doesn't work.

For consistency, it seems like it would be a top-level argument along with "--debug", "--releasever", "--installroot" etc, all of which are setup as the "preconf" variables.

The work-around for this is to use "--releasever", which achieves the same thing.  

[1] http://yum.baseurl.org/gitweb?p=yum.git;a=blob;f=yum/config.py;h=0dcbc6a6f56fb91394045c945739a1a6fbe5584c;hb=HEAD#l1055