3 files changed, 28 insertions, 7 deletions
diff --git a/actionpack/CHANGELOG b/actionpack/CHANGELOG
index 33d3342a47..079bddffd7 100644
--- a/actionpack/CHANGELOG
+++ b/actionpack/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Make sure passed routing options are not mutated by routing code. #5314 [Blair Zajac]
+
 * Make sure changing the controller from foo/bar to bing/bang does not change relative to foo. [Jamis Buck]
 
 * Escape the path before routing recognition. #3671
diff --git a/actionpack/lib/action_controller/routing.rb b/actionpack/lib/action_controller/routing.rb
index 14921c3ac0..8638a1afb2 100644
--- a/actionpack/lib/action_controller/routing.rb
+++ b/actionpack/lib/action_controller/routing.rb
@@ -670,9 +670,10 @@ module ActionController
       # segments are passed alongside in order to distinguish between default values
       # and requirements.
       def divide_route_options(segments, options)
-        requirements = options.delete(:requirements) || {}
-        defaults     = options.delete(:defaults)     || {}
-        conditions   = options.delete(:conditions)   || {}
+        options = options.dup
+        requirements = (options.delete(:requirements) || {}).dup
+        defaults     = (options.delete(:defaults)     || {}).dup
+        conditions   = (options.delete(:conditions)   || {}).dup
 
         path_keys = segments.collect { |segment| segment.key if segment.respond_to?(:key) }.compact
         options.each do |key, value|
@@ -1088,4 +1089,4 @@ module ActionController
 
     Routes = RouteSet.new
   end
-end
-\ No newline at end of file
+end
diff --git a/actionpack/test/controller/routing_test.rb b/actionpack/test/controller/routing_test.rb
index 44e986e3d5..8838ba841e 100644
--- a/actionpack/test/controller/routing_test.rb
+++ b/actionpack/test/controller/routing_test.rb
@@ -863,11 +863,29 @@ class RouteTest < Test::Unit::TestCase
 end
 
 class RouteBuilderTest < Test::Unit::TestCase
-  
+
   def builder
-    @bulider ||= ROUTING::RouteBuilder.new
+    @builder ||= ROUTING::RouteBuilder.new
   end
-  
+
+  def build(path, options)
+    builder.build(path, options)
+  end
+
+  def test_options_should_not_be_modified
+    requirements1 = { :id => /\w+/, :controller => /(?:[a-z](?:-?[a-z]+)*)/ }
+    requirements2 = requirements1.dup
+
+    assert_equal requirements1, requirements2
+
+    with_options(:controller => 'folder',
+                 :requirements => requirements2) do |m|
+      m.build 'folders/new', :action => 'new'
+    end
+
+    assert_equal requirements1, requirements2
+  end
+
   def test_segment_for_static
     segment, rest = builder.segment_for 'ulysses'
     assert_equal '', rest