Eu também tive o mesmo problema, mas o seguinte funcionou para mim
git clone https://github.com/openstack-dev/devstack.git
ou
git clone git://git.openstack.org/openstack-dev/devstack
$ sudo apt-get install git
[sudo] password for shrihari:
Reading package lists...
Done Building dependency tree
Reading state information...
Done git is already the newest version. 0 upgraded, 0 newly installed, 0 to remove and 6 not upgraded.
Além disso, estou tentando instalar o devstack, mas algum erro de rede depois de executar o seguinte:
$ git clone https://git.openstack.org/openstack-dev/devstack
Cloning into 'devstack'...
fatal: unable to access 'https://git.openstack.org/openstack-dev/devstack/': Failed to connect to git.openstack.org port 443: Network is unreachable
Eu também tive o mesmo problema, mas o seguinte funcionou para mim
git clone https://github.com/openstack-dev/devstack.git
ou
git clone git://git.openstack.org/openstack-dev/devstack