make this work with stretch

tasks/main.yml

@@ -1,9 +1,18 @@
-- name: install jessie-backports apt list
+- name: install backports apt list
   apt_repository:
-    filename: jessie-backports
-    repo: "deb http://ftp.de.debian.org/debian jessie-backports main"
+    filename: backports
+    repo: "deb http://ftp.de.debian.org/debian {{ansible_distribution_release}}-backports main"
 
-- name: install jessie-backports sources apt list
+- name: install backports sources apt list
   apt_repository:
-    filename: jessie-backports
-    repo: "deb-src http://ftp.de.debian.org/debian jessie-backports main"
+    filename: backports
+    repo: "deb-src http://ftp.de.debian.org/debian {{ansible_distribution_release}}-backports main"
+
+- name: remove obsolete apt lists
+  file: path=/etc/apt/sources.list.d/{{ item }}-backports.list state=absent
+  with_items:
+    - jessie
+    - stretch
+
+- name: update apt cache
+  apt: update_cache=yes