3 files changed, 34 insertions, 1 deletions
diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index a5fd7b5f25..43fd727500 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,4 +1,8 @@
 ## Rails 4.0.0 (unreleased) ##
+*   Fixed a bug that ignores constraints on a glob route. This was caused because the constraint
+    regular expression is overwritten when the `routes.rb` file is processed. Fixes #7924
+
+    *Maura Fitzgerald*
 
 *   More descriptive error messages when calling `render :partial` with
     an invalid `:layout` argument.
diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index 0c19b493ab..a3a8a1b509 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -158,7 +158,7 @@ module ActionDispatch
           def requirements
             @requirements ||= (@options[:constraints].is_a?(Hash) ? @options[:constraints] : {}).tap do |requirements|
               requirements.reverse_merge!(@scope[:constraints]) if @scope[:constraints]
-              @options.each { |k, v| requirements[k] = v if v.is_a?(Regexp) }
+              @options.each { |k, v| requirements[k] ||= v if v.is_a?(Regexp) }
             end
           end
 
diff --git a/actionpack/test/dispatch/routing_test.rb b/actionpack/test/dispatch/routing_test.rb
index 4f5d8fdb7c..cb5299e8d3 100644
--- a/actionpack/test/dispatch/routing_test.rb
+++ b/actionpack/test/dispatch/routing_test.rb
@@ -3065,6 +3065,35 @@ class TestConstraintsAccessingParameters < ActionDispatch::IntegrationTest
   end
 end
 
+class TestGlobRoutingMapper < ActionDispatch::IntegrationTest
+  Routes = ActionDispatch::Routing::RouteSet.new.tap do |app|
+    app.draw do
+      ok = lambda { |env| [200, { 'Content-Type' => 'text/plain' }, []] }
+
+      get "/*id" => redirect("/not_cars"), :constraints => {id: /dummy/}
+      get "/cars" => ok
+    end
+  end
+
+  #include Routes.url_helpers
+  def app; Routes end
+
+  def test_glob_constraint
+    get "/dummy"
+    assert_equal "301", @response.code
+    assert_equal "/not_cars", @response.header['Location'].match('/[^/]+$')[0]
+  end
+
+  def test_glob_constraint_skip_route
+    get "/cars"
+    assert_equal "200", @response.code
+  end
+  def test_glob_constraint_skip_all
+    get "/missing"
+    assert_equal "404", @response.code
+  end
+end
+
 class TestOptimizedNamedRoutes < ActionDispatch::IntegrationTest
   Routes = ActionDispatch::Routing::RouteSet.new.tap do |app|
     app.draw do