service-wrapper: 16.04.0 -> 19.04

pkgs/os-specific/linux/service-wrapper/default.nix

@@ -2,7 +2,7 @@
 
 let
   name = "service-wrapper-${version}";
-  version = "16.04.0"; # Ajar to Ubuntu Release
+  version = "19.04"; # Akin to Ubuntu Release
 in
 runCommand "${name}" {
   script = substituteAll {
@@ -17,6 +17,7 @@ runCommand "${name}" {
     license     = licenses.gpl2Plus;
     platforms   = platforms.linux;
     maintainers = with maintainers; [ DerTim1 ];
+    # Shellscript has been modified but upstream source is: https://git.launchpad.net/ubuntu/+source/init-system-helpers
   };
 }
 ''