[toolchains] Fix #393 - Cancelling edition generates a 404 (NOT FOUND)

beat/web/toolchains/templates/toolchains/edition.html

@@ -205,7 +205,11 @@ function setupEditor(databases, toolchains)
   };
 
   toolchain_editor.callbacks.onClose = function(declaration) {
+{% if not edition %}
+    window.location = '{% url "toolchains:list" toolchain_author %}';
+{% else %}
     window.location = '{% url "toolchains:view" toolchain_author toolchain_name toolchain_version %}';
+{% endif %}
   };
 }