diff --git a/src/pkg/net/http/serve_test.go b/src/pkg/net/http/serve_test.go
index 7ad1395a62..a040f2738b 100644
--- a/src/pkg/net/http/serve_test.go
+++ b/src/pkg/net/http/serve_test.go
@@ -77,10 +77,15 @@ type rwTestConn struct {
 	io.Reader
 	io.Writer
 	noopConn
-	closec chan bool // if non-nil, send value to it on close
+
+	closeFunc func() error // called if non-nil
+	closec    chan bool    // else, if non-nil, send value to it on close
 }
 
 func (c *rwTestConn) Close() error {
+	if c.closeFunc != nil {
+		return c.closeFunc()
+	}
 	select {
 	case c.closec <- true:
 	default:
diff --git a/src/pkg/net/http/transport.go b/src/pkg/net/http/transport.go
index ea02ffb53a..c14ee3aa68 100644
--- a/src/pkg/net/http/transport.go
+++ b/src/pkg/net/http/transport.go
@@ -715,7 +715,10 @@ func (pc *persistConn) readLoop() {
 			resp.Body = &bodyEOFSignal{body: resp.Body}
 		}
 
-		if err != nil || resp.Close || rc.req.Close {
+		if err != nil || resp.Close || rc.req.Close || resp.StatusCode <= 199 {
+			// Don't do keep-alive on error if either party requested a close
+			// or we get an unexpected informational (1xx) response.
+			// StatusCode 100 is already handled above.
 			alive = false
 		}
 
diff --git a/src/pkg/net/http/transport_test.go b/src/pkg/net/http/transport_test.go
index 75ab5dd7d8..9f64a6e4b5 100644
--- a/src/pkg/net/http/transport_test.go
+++ b/src/pkg/net/http/transport_test.go
@@ -1416,18 +1416,28 @@ func TestTransportReading100Continue(t *testing.T) {
 		for {
 			n++
 			req, err := ReadRequest(br)
+			if err == io.EOF {
+				return
+			}
 			if err != nil {
 				t.Error(err)
 				return
 			}
 			slurp, err := ioutil.ReadAll(req.Body)
-			if err != nil || string(slurp) != reqBody(n) {
-				t.Errorf("Server got %q, %v; want 'body'", slurp, err)
+			if err != nil {
+				t.Errorf("Server request body slurp: %v", err)
 				return
 			}
 			id := req.Header.Get("Request-Id")
+			resCode := req.Header.Get("X-Want-Response-Code")
+			if resCode == "" {
+				resCode = "100 Continue"
+				if string(slurp) != reqBody(n) {
+					t.Errorf("Server got %q, %v; want %q", slurp, err, reqBody(n))
+				}
+			}
 			body := fmt.Sprintf("Response number %d", n)
-			v := []byte(strings.Replace(fmt.Sprintf(`HTTP/1.1 100 Continue
+			v := []byte(strings.Replace(fmt.Sprintf(`HTTP/1.1 %s
 Date: Thu, 28 Feb 2013 17:55:41 GMT
 
 HTTP/1.1 200 OK
@@ -1435,7 +1445,7 @@ Content-Type: text/html
 Echo-Request-Id: %s
 Content-Length: %d
 
-%s`, id, len(body), body), "\n", "\r\n", -1))
+%s`, resCode, id, len(body), body), "\n", "\r\n", -1))
 			w.Write(v)
 			if id == reqID(numReqs) {
 				return
@@ -1451,6 +1461,11 @@ Content-Length: %d
 			conn := &rwTestConn{
 				Reader: cr,
 				Writer: sw,
+				closeFunc: func() error {
+					sw.Close()
+					cw.Close()
+					return nil
+				},
 			}
 			go send100Response(cw, sr)
 			return conn, nil
@@ -1459,21 +1474,38 @@ Content-Length: %d
 	}
 	defer tr.CloseIdleConnections()
 	c := &Client{Transport: tr}
-	for i := 1; i <= numReqs; i++ {
-		req, _ := NewRequest("POST", "http://dummy.tld/", strings.NewReader(reqBody(i)))
-		req.Header.Set("Request-Id", reqID(i))
+
+	testResponse := func(req *Request, name string, wantCode int) {
 		res, err := c.Do(req)
 		if err != nil {
-			t.Fatalf("Do (i=%d): %v", i, err)
+			t.Fatalf("%s: Do: %v", name, err)
 		}
-		if res.StatusCode != 200 {
-			t.Fatalf("Response Statuscode=%d; want 200 (i=%d): %v", res.StatusCode, i, err)
+		if res.StatusCode != wantCode {
+			t.Fatalf("%s: Response Statuscode=%d; want %d", name, res.StatusCode, wantCode)
+		}
+		if id, idBack := req.Header.Get("Request-Id"), res.Header.Get("Echo-Request-Id"); id != "" && id != idBack {
+			t.Errorf("%s: response id %q != request id %q", name, idBack, id)
 		}
 		_, err = ioutil.ReadAll(res.Body)
 		if err != nil {
-			t.Fatalf("Slurp error (i=%d): %v", i, err)
+			t.Fatalf("%s: Slurp error: %v", name, err)
 		}
 	}
+
+	// Few 100 responses, making sure we're not off-by-one.
+	for i := 1; i <= numReqs; i++ {
+		req, _ := NewRequest("POST", "http://dummy.tld/", strings.NewReader(reqBody(i)))
+		req.Header.Set("Request-Id", reqID(i))
+		testResponse(req, fmt.Sprintf("100, %d/%d", i, numReqs), 200)
+	}
+
+	// And some other informational 1xx but non-100 responses, to test
+	// we return them but don't re-use the connection.
+	for i := 1; i <= numReqs; i++ {
+		req, _ := NewRequest("POST", "http://other.tld/", strings.NewReader(reqBody(i)))
+		req.Header.Set("X-Want-Response-Code", "123 Sesame Street")
+		testResponse(req, fmt.Sprintf("123, %d/%d", i, numReqs), 123)
+	}
 }
 
 type proxyFromEnvTest struct {