Fix unarchive task in Gitian role

As of Ansible 2.2.0, copy and remote_src are mutually exclusive.
Also adds IdentitiesOnly=yes to SSH options.

ansible.cfg

@@ -6,6 +6,6 @@ host_key_checking = False
 timeout = 60
 
 [ssh_connection]
-ssh_args = -o ControlMaster=auto -o ControlPersist=300s -o ConnectTimeout=60
+ssh_args = -o ControlMaster=auto -o ControlPersist=300s -o ConnectTimeout=60 -o IdentitiesOnly=yes
 pipelining = True
 scp_if_ssh = True

roles/gitian/tasks/main.yml

@@ -92,7 +92,6 @@
   unarchive:
     src: "{{ vm_builder_url }}"
     dest: "{{ download_directory }}"
-    copy: no
     remote_src: yes
 
 - name: Install VM builder Python module.