fix re-enter middleware bug V2

gin.go

@@ -637,10 +637,12 @@ func (engine *Engine) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 // Disclaimer: You can loop yourself to deal with this, use wisely.
 func (engine *Engine) HandleContext(c *Context) {
 	oldIndexValue := c.index
+	oldHandlers := c.handlers
 	c.reset()
 	engine.handleHTTPRequest(c)
 
 	c.index = oldIndexValue
+	c.handlers = oldHandlers
 }
 
 func (engine *Engine) handleHTTPRequest(c *Context) {

gin_test.go

@@ -572,6 +572,44 @@ func TestEngineHandleContextManyReEntries(t *testing.T) {
 	assert.Equal(t, int64(expectValue), middlewareCounter)
 }
 
+func TestEngineHandleContextPreventsMiddlewareReEntry(t *testing.T) {
+	// given
+	var handlerCounterV1, handlerCounterV2, middlewareCounterV1 int64
+
+	r := New()
+	v1 := r.Group("/v1")
+	{
+		v1.Use(func(c *Context) {
+			atomic.AddInt64(&middlewareCounterV1, 1)
+		})
+		v1.GET("/test", func(c *Context) {
+			atomic.AddInt64(&handlerCounterV1, 1)
+			c.Status(http.StatusOK)
+		})
+	}
+
+	v2 := r.Group("/v2")
+	{
+		v2.GET("/test", func(c *Context) {
+			c.Request.URL.Path = "/v1/test"
+			r.HandleContext(c)
+		}, func(c *Context) {
+			atomic.AddInt64(&handlerCounterV2, 1)
+		})
+	}
+
+	// when
+	responseV1 := PerformRequest(r, "GET", "/v1/test")
+	responseV2 := PerformRequest(r, "GET", "/v2/test")
+
+	// then
+	assert.Equal(t, 200, responseV1.Code)
+	assert.Equal(t, 200, responseV2.Code)
+	assert.Equal(t, int64(2), handlerCounterV1)
+	assert.Equal(t, int64(2), middlewareCounterV1)
+	assert.Equal(t, int64(1), handlerCounterV2)
+}
+
 func TestPrepareTrustedCIRDsWith(t *testing.T) {
 	r := New()