fix: fixed crash when gzip was enabled

vendor/github.com/go-macaron/gzip/.travis.yml

@@ -1,14 +0,0 @@
-sudo: false
-language: go
-
-go:
-  - 1.3
-  - 1.4
-  - 1.5
-  - tip
-
-script: go test -v -cover -race
-
-notifications:
-  email:
-    - u@gogs.io

vendor/github.com/go-macaron/gzip/gzip.go

@@ -86,7 +86,10 @@ func Gziper(options ...Options) macaron.Handler {
 		gzw := gzipResponseWriter{gz, ctx.Resp}
 		ctx.Resp = gzw
 		ctx.MapTo(gzw, (*http.ResponseWriter)(nil))
-		if ctx.Render != nil {
+
+		// Check if render middleware has been registered,
+		// if yes, we need to modify ResponseWriter for it as well.
+		if _, ok := ctx.Render.(*macaron.DummyRender); !ok {
 			ctx.Render.SetResponseWriter(gzw)
 		}