main.go

package main

import (
    "github.com/elazarl/goproxy"
    "io/ioutil"
    "log"
    "net/http"                                                                                                                                                                                                                                                                                                                                                               
)

func main() {
    proxy := goproxy.NewProxyHttpServer()

    proxy.OnRequest().HandleConnect(goproxy.AlwaysMitm)

    proxy.OnRequest(goproxy.DstHostIs("review.openstack.org:443")).DoFunc(
        func(r *http.Request, ctx *goproxy.ProxyCtx) (*http.Request, *http.Response) {
            log.Println(r.URL.Path)
            if r.URL.Path == "/projects/openstack-infra/config/config" {  // workaround for
                r.URL.Path = "/projects/openstack-infra%2Fconfig/config"  // https://github.com/elazarl/goproxy/issues/61
            }
            if r.URL.Path == "/static/hideci.js" {
                log.Println("Hijacked!")
                hideci, _ := ioutil.ReadFile("/home/mjg/hideci.js") // Change as appropriate
                return r, goproxy.NewResponse(r,
                    goproxy.ContentTypeText, http.StatusOK,
                    string(hideci))
            }
            return r, nil
        })

    log.Fatal(http.ListenAndServe(":8080", proxy))
}

• run this with "go run main.go"
• point browser's http proxy setting to localhost:8080
• accept warnings about certificates (you are MITM-ing yourself, after all)

Also have to run go get github.com/elazarl/goproxy