install_arch: verify bootstrap image signature

Fixes #458 (closed).

roles/install_arch/tasks/main.yml

@@ -9,7+9,7 @@
 
 - name: Make sure all required packages are installed in the rescue system for installation
   apk: name=sgdisk,btrfs-progs,tar update_cache=yes
   when: ansible_facts['os_family'] == "Alpine"
 
 - name: Create GRUB embed partitions
   command: sgdisk -g --clear -n 1:0:+1M {{ item }} -c 1:boot -t 1:ef02
@@ -44,7+44,7 @@
   get_url:
     url: https://geo.mirror.pkgbuild.com/iso/{{ bootstrap_version }}/archlinux-bootstrap-x86_64.tar.gz
     dest: /tmp/
     mode: 0644
 
 - name: Download bootstrap signature
   get_url:
@@ -65,7+65,7 @@
 - name: Extract boostrap image  # noqa risky-file-permissions
   unarchive:
     src: /tmp/archlinux-bootstrap-x86_64.tar.gz
-    dest: /tmpgpg --keyserver-options auto-key-retrieve --verifys/dev
+    dest: /tmp
+    remote_src: true
+    creates: /tmp/root.x86_64
   when: valid_key.stdout_lines[1] | trim == gpg_info.stderr_lines[2].split()[-1] | trim
 
 - name: Copy resolv.conf to bootstrap chroot