...

tasks/guix.yml

@@ -54,7 +54,7 @@
 
 - name: Install packages.
   command:
-    cmd: /usr/bin/bash -l -c 'guix package -c4 -m /etc/guix_manifest.scm'
+    cmd: /usr/bin/bash -l -c 'guix package -c4 -m /etc/guix_manifest.scm --fallback'
   tags: guix-inst-pkg
   become_user: "{{ item.login }}"
   retries: 10