Allow HTTP Headers not in spec

potential fix for #3772

packages/node_modules/@node-red/nodes/core/network/21-httprequest.html

@@ -91,6 +91,11 @@
         <label for="node-input-senderr" style="width: auto" data-i18n="httpin.senderr"></label>
     </div>
 
+    <div class="form-row">
+        <input type="checkbox" id="node-input-insecureHTTPParser" style="display: inline-block; width: auto; vertical-align: top;">
+        <label for="node-input-insecureHTTPParser", style="width: auto;" data-i18n="httpin.insecureHTTPParser"></label>
+    </div>
+
 
     <div class="form-row">
         <label for="node-input-ret"><i class="fa fa-arrow-left"></i> <span data-i18n="httpin.label.return"></span></label>
@@ -227,6 +232,7 @@
             persist: {value:false},
             proxy: {type:"http proxy",required: false,
                     label:RED._("node-red:httpin.proxy-config") },
+            insecureHTTPParser: {value: false},
             authType: {value: ""},
             senderr: {value: false},
             headers: { value: [] }
@@ -338,6 +344,12 @@
             } else {
                 $("#node-input-useProxy").prop("checked", false);
             }
+
+            if (node.insecureHTTPParser) {
+                $("node-intput-insecureHTTPParser").prop("checked", true)
+            } else {
+                $("node-intput-insecureHTTPParser").prop("checked", false)
+            }
             updateProxyOptions();
             $("#node-input-useProxy").on("click", function() {
                 updateProxyOptions();

packages/node_modules/@node-red/nodes/core/network/21-httprequest.js

@@ -244,6 +244,10 @@ in your Node-RED user directory (${RED.settings.userDir}).
                                 delete options.headers[h];
                             }
                         })
+
+                        if (node.insecureHTTPParser) {
+                            options.insecureHTTPParser = true
+                        }
                     }
                 ],
                 beforeRedirect: [

packages/node_modules/@node-red/nodes/locales/en-US/messages.json

@@ -554,7 +554,8 @@
         },
         "status": {
             "requesting": "requesting"
-        }
+        },
+        "insecureHTTPParser": "Lenient HTTP Header Parsing"
     },
     "websocket": {
         "label": {