Request context is passed to PushIfNotCancelled instead of VU context

[cuonglm]

This script fails with current go master:

import http from "k6/http";
import { check } from "k6";
import { Counter } from "k6/metrics";

let statusCheck = { "status is 200": (r) => r.status === 200 }
let myCounter = new Counter("setup_teardown");

export let options = {
	iterations: 5,
	thresholds: {
		"setup_teardown": ["count == 2"],
		"iterations": ["count == 5"],
		"http_reqs": ["count == 7"],
	},
};

export function setup() {
	check(http.get("http://test.loadimpact.com"), statusCheck) && myCounter.add(1);
};

export default function () {
	check(http.get("http://test.loadimpact.com"), statusCheck);
};

export function teardown() {
	check(http.get("http://test.loadimpact.com"), statusCheck) && myCounter.add(1);
};

$ go run main.go run ./t.js

          /\      |‾‾|  /‾‾/  /‾/
     /\  /  \     |  |_/  /  / /
    /  \/    \    |      |  /  ‾‾\
   /          \   |  |‾\  \ | (_) |
  / __________ \  |__|  \__\ \___/ .io

  execution: local
     output: -
     script: ./t.js

    duration: -,  iterations: 5
         vus: 1, max: 1

    done [==========================================================] 5 / 5

    ✓ status is 200

    checks.....................: 100.00% ✓ 7   ✗ 0
    data_received..............: 9.7 kB  14 kB/s
    data_sent..................: 623 B   913 B/s
    http_req_blocked...........: avg=134.9ms  min=110.1ms  med=134.9ms  max=159.7ms  p(90)=154.74ms p(95)=157.22ms
    http_req_connecting........: avg=110.37ms min=110.05ms med=110.37ms max=110.7ms  p(90)=110.63ms p(95)=110.66ms
    http_req_duration..........: avg=112.33ms min=112.09ms med=112.33ms max=112.56ms p(90)=112.51ms p(95)=112.54ms
    http_req_receiving.........: avg=133µs    min=98µs     med=133µs    max=168µs    p(90)=161µs    p(95)=164.5µs
    http_req_sending...........: avg=62.5µs   min=60µs     med=62.5µs   max=65µs     p(90)=64.5µs   p(95)=64.75µs
    http_req_tls_handshaking...: avg=0s       min=0s       med=0s       max=0s       p(90)=0s       p(95)=0s
    http_req_waiting...........: avg=112.13ms min=111.93ms med=112.13ms max=112.33ms p(90)=112.29ms p(95)=112.31ms
  ✗ http_reqs..................: 2       2.931485/s
    iteration_duration.........: avg=168.24ms min=113.77ms med=114.05ms max=272.5ms  p(90)=245.25ms p(95)=258.87ms
  ✓ iterations.................: 5       7.328713/s
  ✓ setup_teardown.............: 2       2.931485/s
    vus........................: 1       min=1 max=1
    vus_max....................: 1       min=1 max=1

There are two problems for current code base:

• Client.Timeout is set and intended to pass to request context, but it doesn't due to the bug in Go standard library. If we set the request context timeout explicitly, it leads to the second problem.
• Currently, the request context is passed to PushIfNotCancelled, which is completely wrong, since when we want to use VU context instead.