I am afraid that the outcome of my testing is bad news actually. There is something that is not consistent. I need to spare time to redo the testing and report the results.
I tested using the most basic flow possible. Just an http request node. See below.
[{"id":"a4f5363d.1c4968","type":"tab","label":"Flow 6","disabled":false,"info":""},{"id":"b30a55f6.9598f8","type":"debug","z":"a4f5363d.1c4968","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","x":610,"y":180,"wires":[]},{"id":"41cc11c9.49e21","type":"inject","z":"a4f5363d.1c4968","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":220,"y":180,"wires":[["c9495473.5ba4f8"]]},{"id":"c9495473.5ba4f8","type":"http request","z":"a4f5363d.1c4968","name":"","method":"GET","ret":"obj","paytoqs":false,"url":"http://41.192.149.206:8080/query?select=%5Btime.iso,ch1.d2,ch1.amps.d2,ch1.va.d2,ch1.pf.d2%5D&begin=h-30m&end=h&group=30m&format=json&header=yes'","tls":"","persist":false,"proxy":"","authType":"","x":430,"y":180,"wires":[["b30a55f6.9598f8"]]}]
HTTP Toolkit is an external tool to intercept HTTP requests and responses. It is not related to Node-RED.
I tested in my Windows machine. I wish I could test on a Raspberry PI to compare the results, but not possible for some time.
1 Mar 15:21:04 - [info] Node-RED version: v1.0.3
1 Mar 15:21:04 - [info] Node.js version: v8.11.1
1 Mar 15:21:04 - [info] Windows_NT 10.0.17763 x64 LE