Redirect users in homepage to homepage after login

For reasons I'm not sure about, the homepage (and the welcome pages)
were an exception in our "redirect users to the same page they were"
policy.

I'm not sure about the welcome pages (no test was present indicating
they should behave in a special way), but in the case of the home page,
it was a bit annoying to be redirected to a different place after
signing in.

app/controllers/application_controller.rb

@@ -107,7 +107,7 @@ class ApplicationController < ActionController::Base
     end
 
     def set_return_url
-      if !devise_controller? && controller_name != "welcome" && is_navigational_format?
+      if !devise_controller? && is_navigational_format?
         store_location_for(:user, request.fullpath)
       end
     end

spec/system/sessions_spec.rb

@@ -6,8 +6,10 @@ describe "Sessions" do
     debate = create(:debate)
 
     visit debate_path(debate)
-
-    login_through_form_as(user)
+    click_link "Sign in"
+    fill_in "user_login", with: user.email
+    fill_in "user_password", with: user.password
+    click_button "Enter"
 
     expect(page).to have_content("You have been signed in successfully")
     expect(page).to have_current_path(debate_path(debate))
@@ -30,4 +32,17 @@ describe "Sessions" do
 
     expect(page).to have_current_path budget_investments_path(heading.budget, heading_id: "outskirts")
   end
+
+  scenario "Sign in redirects to the homepage if the user was there" do
+    user = create(:user, :level_two)
+
+    visit debates_path
+    visit "/"
+    click_link "Sign in"
+    fill_in "user_login", with: user.email
+    fill_in "user_password", with: user.password
+    click_button "Enter"
+
+    expect(page).to have_current_path "/"
+  end
 end