`merge` in utils convert an array post data to an object

Summary

try

let url = '/dsk',
let data = {
    dsk: ['a1', 'a2']
}
let config = {
    baseURL: 'http://8.8.8.8',
    data
}

axios.post(url, data, {config}).then(resp => { console.log(resp.config.data) })

get resp.config.data

{"baseURL": "http://8.8.8.8", "url": "/dsk", "data": {"0": "a1", "1": "a2"}}

this config data is not expect.

Context

• axios version: v0.18.0
• Environment: node v10.4.1

[seedlinktech-william]

I have met same situation. What I used for workaround is delete the data in config, like:

let url = '/dsk',
let data = {
    dsk: ['a1', 'a2']
}
let config = {
    baseURL: 'http://8.8.8.8',
    // data
}

axios.post(url, data, config).then(resp => { console.log(resp.config.data) })

When axios.post be invoked, it will check its arguments and compare the data with config.data. If config.data is false value, it will using the data directly. Then the merge will not be called.

[chinesedfan]

Closed in favor of #2567.