Install build private key too

This will allow all nodes to SSH to each other, which should facilitate
some multi-node jobs that need this enabled.

We set "force" to "no" on the copies since this is in the base job's
pre.yml, meaning it should run before basically anything else.

Change-Id: If11f05f5cced71f6e9f634195e628ea68813c4cf

roles/add-build-sshkey/tasks/create-key-and-replace.yaml

@@ -3,12 +3,32 @@
   delegate_to: localhost
   run_once: true
 
-- name: Distribute it to all nodes
+- name: Enable access via build key on all nodes
   authorized_key:
     user: "{{ ansible_ssh_user }}"
     state: present
     key: "{{ lookup('file', zuul_temp_ssh_key + '.pub') }}"
 
+- name: Make sure user has a .ssh
+  file:
+    state: directory
+    path: "~/.ssh"
+    mode: 0700
+
+- name: Install build private key as SSH key on all nodes
+  copy:
+    src: "{{ zuul_temp_ssh_key }}"
+    dest: "~/.ssh/id_rsa"
+    mode: 0600
+    force: no
+
+- name: Install build public key as SSH key on all nodes
+  copy:
+    src: "{{ zuul_temp_ssh_key }}.pub"
+    dest: "~/.ssh/id_rsa.pub"
+    mode: 0644
+    force: no
+
 - name: Remove all keys from local agent
   command: ssh-add -D
   delegate_to: localhost