Ensure back button skips forms. Resolves #4055

frontend/src/metabase/questions/collections.js

 
 import { createAction, createThunkAction, handleActions, combineReducers } from "metabase/lib/redux";
 import { reset } from 'redux-form';
-import { push } from "react-router-redux";
+import { replace } from "react-router-redux";
 import Urls from "metabase/lib/urls";
 
 import _ from "underscore";
@@ -37,7 +37,8 @@ export const saveCollection = createThunkAction(SAVE_COLLECTION, (collection) =>
             if (response.id != null) {
                 dispatch(reset("collection"));
             }
-            dispatch(push(Urls.collection(response)));
+            // use `replace` so form url doesn't appear in history
+            dispatch(replace(Urls.collection(response)));
             return response;
         } catch (e) {
             // redux-form expects an object with either { field: error } or { _error: error }