I tried what you suggested and got:
git clone ssh://dcnomura@sources.redhat.com/git/systemtap.git git-ssh
Initialize git-ssh/.git
Initialized empty Git repository in /home/dcn/systemtap/git/git-ssh/.git/
Permission denied (publickey,gssapi-with-mic).
fatal: The remote end hung up unexpectedly
I also tried the modification you suggested to .ssh/config
I tried to just ssh to sources.redhat.com and got:
vervainp2.rchland.ibm.com% ssh dcnomura@sources.redhat.com
Permission denied (publickey,gssapi-with-mic).
I think the ssh id_rsa.pub is not working..
Any suggestions on how to debug this problem?