Revert "Merge pull request #27775 from domcleal/27774-format-reset"

This reverts commit c6f9f8c28a, reversing
changes made to c309073c74.

Reason: This is fixing the behavior in the wrong place. Now the request
path after the request is nil and there is no way to assert that.
Also the test that was added in that PR also fails in 4.2 where the
reporter says it was passing. The reason the bahavior changed between
Rails 4.2 and Rails 5 is that the format in the path is now respected.
The correct way to fix the problem is not doign two requests in the same
controller test and use integrations tests. This change caused a
regression between Rails 5.0.1 and 5.0.2.

actionpack/lib/action_controller/test_case.rb

@@ -534,7 +534,6 @@ module ActionController
             @request.delete_header "HTTP_ACCEPT"
           end
           @request.query_string = ""
-          @request.env.delete "PATH_INFO"
 
           @response.sent!
         end

actionpack/test/controller/test_case_test.rb

@@ -679,6 +679,11 @@ XML
     assert_equal "baz", @request.filtered_parameters[:foo]
   end
 
+  def test_path_is_kept_after_the_request
+    get :test_params, params: { id: "foo" }
+    assert_equal "foo", @request.path
+  end
+
   def test_path_params_reset_between_request
     get :test_params, params: { id: "foo" }
     assert_equal "foo", @request.path_parameters[:id]
@@ -728,20 +733,6 @@ XML
     assert_equal "text/html", @response.body
   end
 
-  def test_request_path_info_and_format_reset
-    get :test_format, format: "json"
-    assert_equal "application/json", @response.body
-
-    get :test_uri, format: "json"
-    assert_equal "/test_case_test/test/test_uri.json", @response.body
-
-    get :test_format
-    assert_equal "text/html", @response.body
-
-    get :test_uri
-    assert_equal "/test_case_test/test/test_uri", @response.body
-  end
-
   def test_request_format_kwarg_overrides_params
     get :test_format, format: "json", params: { format: "html" }
     assert_equal "application/json", @response.body