From c329c7d193285eb0aeac7892896766be20a84c4c Mon Sep 17 00:00:00 2001
From: bign8 <big.nate.w@gmail.com>
Date: Fri, 25 Dec 2015 13:16:04 -0700
Subject: [PATCH 1/2] Potential fix for #20

---
 mux.go | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/mux.go b/mux.go
index 68c4ea5..aabe995 100644
--- a/mux.go
+++ b/mux.go
@@ -59,6 +59,12 @@ func (r *Router) Match(req *http.Request, match *RouteMatch) bool {
 			return true
 		}
 	}
+
+	// Closest match for a router (includes sub-routers)
+	if r.NotFoundHandler != nil {
+		match.Handler = r.NotFoundHandler
+		return true
+	}
 	return false
 }
 
@@ -89,10 +95,7 @@ func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 		setCurrentRoute(req, match.Route)
 	}
 	if handler == nil {
-		handler = r.NotFoundHandler
-		if handler == nil {
-			handler = http.NotFoundHandler()
-		}
+		handler = http.NotFoundHandler()
 	}
 	if !r.KeepContext {
 		defer context.Clear(req)
@@ -324,11 +327,15 @@ func CurrentRoute(r *http.Request) *Route {
 }
 
 func setVars(r *http.Request, val interface{}) {
-	context.Set(r, varsKey, val)
+	if val != nil {
+		context.Set(r, varsKey, val)
+	}
 }
 
 func setCurrentRoute(r *http.Request, val interface{}) {
-	context.Set(r, routeKey, val)
+	if val != nil {
+		context.Set(r, routeKey, val)
+	}
 }
 
 // ----------------------------------------------------------------------------

From 82a9c170d40582ee65ff8af081485e5e325fb4a0 Mon Sep 17 00:00:00 2001
From: Nate Woods <big.nate.w@gmail.com>
Date: Sat, 26 Dec 2015 00:09:21 -0700
Subject: [PATCH 2/2] Covering change with unit test

This test focuses on the feature of allowing sub-routers error handlers to precede the parents, rather than the code change required to provide this functionality.
---
 mux_test.go | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/mux_test.go b/mux_test.go
index d1eae92..1ea439a 100644
--- a/mux_test.go
+++ b/mux_test.go
@@ -1123,6 +1123,30 @@ func TestWalkNested(t *testing.T) {
 	}
 }
 
+func TestSubrouterErrorHandling(t *testing.T) {
+	superRouterCalled := false
+	subRouterCalled := false
+
+	router := NewRouter()
+	router.NotFoundHandler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		superRouterCalled = true
+	})
+	subRouter := router.PathPrefix("/bign8").Subrouter()
+	subRouter.NotFoundHandler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		subRouterCalled = true
+	})
+
+	req, _ := http.NewRequest("GET", "http://localhost/bign8/was/here", nil)
+	router.ServeHTTP(NewRecorder(), req)
+
+	if superRouterCalled {
+		t.Error("Super router 404 handler called when sub-router 404 handler is available.")
+	}
+	if !subRouterCalled {
+		t.Error("Sub-router 404 handler was not called.")
+	}
+}
+
 // ----------------------------------------------------------------------------
 // Helpers
 // ----------------------------------------------------------------------------