From Fedora Project Wiki
Devel was merged, not FC-5 and FC-6
Fedora Core 5 and 6 continued to use the old CVS and buildsystems until their end of life.
FC-5 was end-of-lifed on Friday June 29th, 2007. No new builds can be done for the FC-5 branch.
FC-6 was end-of-lifed on Friday December 7th, 2007. No new builds can be done for the FC-6 branch.

CVS Changes for devel (and F-7 and newer branches)
Core and Extras development (what has become Fedora 7) have been merged into a single CVS and buildsystem.  1150 source
RPMS from Core were added to /cvs/extras, and it was renamed to /cvs/pkgs.  A symlink from /cvs/extras to /cvs/pkgs has
been added for convenience. old Extras, now a symlink to /cvs/pkgs   /cvs/extras plus all F7 core packages

There is no kerberos gserver on the external CVS.  You must use ssh pubkey authentication to reach

export CVS_RSH='ssh'
cvs co packagename

Buildsystem Changes for devel
The "devel" branch uses koji instead of plague.  Please follow these steps to setup your client for koji.
yum install koji

Existing users of plague, it will copy certs already existing.
If you did not have plague before, it will tell you where to get the certs.
Build Status Web Interface

Why does my build for a formerly-Extras package fail on PPC64?
Extras packages weren't built for PPC64, so if your package requires any package formerly in Extras (either because it
itself used to be in Extras or because you just added the dependency to your formerly-Core package), there may be trouble.
Please DON'T just ExcludeArch: ppc64, instead follow the procedure outlined by Jesse Keating: