Fixed of losing context existing headers in response

src/nodejs/unit-http/http_server.js

@@ -153,9 +153,9 @@ ServerResponse.prototype._removeHeader = function _removeHeader(lc_name) {
         this.headers_count -= value.length;
         this.headers_len -= value.length * name_len;
 
-        value.forEach(function(val) {
-            this.headers_len -= Buffer.byteLength(val + "", 'latin1');
-        });
+        for (let i = 0; i < value.length; i++){
+            this.headers_len -= Buffer.byteLength(value[i] + "", 'latin1');
+        }
 
         return;
     }

test/node/set_header_array_with_override/app.js

@@ -0,0 +1,6 @@
+
+require('http').createServer(function (req, res) {
+    res.setHeader('Set-Cookie', ['tc=one,two,three', 'tc=four,five,six']);
+    res.setHeader('Set-Cookie', ['tc=one,two,three', 'tc=four,five,six', 'tc=seven,eight,nine']);
+    res.end();
+}).listen(8080);

test/test_node_application.py

@@ -234,6 +234,16 @@ def test_node_application_set_header_array():
     ], 'set header array'
 
 
+def test_node_application_set_header_array_with_override():
+    client.load('set_header_array_with_override')
+
+    assert client.get()['headers']['Set-Cookie'] == [
+        'tc=one,two,three',
+        'tc=four,five,six',
+        'tc=seven,eight,nine',
+    ], 'set header array with override'
+
+
 @pytest.mark.skip('not yet')
 def test_node_application_status_message():
     client.load('status_message')