[git] git clone into custom path

git clone https://github.com/openstack/nova.git /opt/stack/nova

local repository is not ~/git/nova but /opt/stack/nova

ref

http://devstack.org/guides/single-machine.html

https://help.ubuntu.com/community/Installation/MinimalCD

Error: Failed to launch instance "kenufirst": Please try again later [Error: Timeout while waiting on RPC response - topic: "network", RPC method: "get_instance_nw_info" info: "<unknown>"].