$ git push origin master
(gnome-ssh-askpass:22648): Gtk-WARNING **: cannot open display:
This occurs because the SSH_ASKPASS environment variable is set to "/usr/libexec/openssh/gnome-ssh-askpass", which is the nice gtk window that pops up when you're running gnome. I don't want this, because I do most of my work over SSH, so simply change SSH_ASKPASS to something else. In my ~/.bashrc
alias git="SSH_ASKPASS='' git"
Then:
$ source ~/.bashrc
Fixes it up.