http_response regression when not following redirects

[mp1409]

Relevant telegraf.conf:

[[inputs.http_response]]
  urls = ["http://<redacted>/"]
  follow_redirects = false

System info:

Distributor ID:	Debian
Description:	Debian GNU/Linux 9.10 (stretch)
Release:	9.10
Codename:	stretch

Telegraf 1.12.0 (git: HEAD 43bb6941)

Steps to reproduce:

I'm monitoring a bunch of HTTP websites that redirect to HTTPS with Grafana and Telegraf's http_response . The HTTPS websites are monitored separately, i.e. I want to monitor the redirections themselves.

Expected behavior:

Based upon the documentation (and working up to Telegraf 1.11.5), I would expect the response code to be a redirection (i.e. 301, 307), and the result code to be 0.

Actual behavior:

Since 1.12.0, the result code is still correct, but the response code is 2 (body_read_error). However, according to the docs, it should be zero.

Additional info:

Log output:

D! Network error while polling http://<redacted>/: Get https://<redacted>/: redirect
D! Failed to read body of HTTP Response : http: read on closed response body

[mp1409]

Works in 1.12.1, thanks!