Avoid text file busy when upgrading etcd binary

roles/etcd/tasks/install_from_github.yml

@@ -33,6 +33,11 @@
     dest: /tmp/etcd.tar.gz
   when: do_install_etcd
 
+# Avoid 'text file busy' when copying over running binary.
+- name: Move old etcd binary out of the way
+  shell: "mv -f /usr/bin/etcd /usr/bin/etcd.old"
+  when: "do_install_etcd and etcd_bin.stat.exists"
+
 # We really want to use 'tar' here and not unarchive because we need
 # --strip-components.
 - name: Extract etcd binary and install contents