At the moment, if you use fedpkg clone, you need to have a account and your ssh key on the fedora server. When you do not have, fedpkg try to use your ssh keys, and then fail once you cannot login :
{{{

$ fedpkg clone cgit
Cloning into cgit...
Enter passphrase for key '/home/misc/.ssh/id_rsa':
Permission denied (publickey).
fatal: The remote end hung up unexpectedly
Traceback (most recent call last):
File "/usr/bin/fedpkg", line 903, in <module>
args.command(args)
File "/usr/bin/fedpkg", line 408, in clone
pyfedpkg.clone(args.module[0], args.user, args.path, args.branch)
File "/usr/lib/python2.6/site-packages/pyfedpkg/init.py", line 287, in clone
_run_command(cmd)
File "/usr/lib/python2.6/site-packages/pyfedpkg/init.py", line 112, in _run_command
raise FedpkgError(e)
pyfedpkg.FedpkgError: Command '['git', 'clone', 'ssh://misc@pkgs.stg.fedoraproject.org/cgit']' returned non-zero exit status 128
}}}

Here is a patch that add a --anonymous switch to the clone operation, so it doesn't try to authenticate at all.