transport.diff

 func (rl *clientConnReadLoop) handleResponse(cs *clientStream, f *MetaHeadersFrame) (*http.Response, error) {
        if f.Truncated {
                return nil, errResponseHeaderListSize
@@ -1750,15 +1762,6 @@ func (rl *clientConnReadLoop) handleResponse(cs *clientStream, f *MetaHeadersFra
                return nil, errors.New("malformed response from server: malformed non-numeric status pseudo header")
        }
 
-       if statusCode == 100 {
-               traceGot100Continue(cs.trace)
-               if cs.on100 != nil {
-                       cs.on100() // forces any write delay timer to fire
-               }
-               cs.pastHeaders = false // do it all again
-               return nil, nil
-       }
-
        header := make(http.Header)
        res := &http.Response{
                Proto:      "HTTP/2.0",
@@ -1783,6 +1786,27 @@ func (rl *clientConnReadLoop) handleResponse(cs *clientStream, f *MetaHeadersFra
                }
        }
 
+       if statusCode >= 100 && statusCode <= 199 {
+               cs.num1xx++
+               const max1xxResponses = 5 // arbitrary bound on number of informational responses, same as net/http
+               if cs.num1xx > max1xxResponses {
+                       return nil, errors.New("http2: too many 1xx informational responses")
+               }
+               if fn := cs.get1xxTraceFunc(); fn != nil {
+                       if err := fn(statusCode, textproto.MIMEHeader(header)); err != nil {
+                               return nil, err
+                       }
+               }
+               if statusCode == 100 {
+                       traceGot100Continue(cs.trace)
+                       if cs.on100 != nil {
+                               cs.on100() // forces any write delay timer to fire
+                       }
+               }
+               cs.pastHeaders = false // do it all again
+               return nil, nil
+       }
+
        streamEnded := f.StreamEnded()
        isHead := cs.req.Method == "HEAD"
        if !streamEnded || isHead {