Description of problem:
If I issue an http (not https) API PUT request against Satellite 6.4.0 (or older) it fails with this message:

{
"error": {"message":"'Content-Type: ' is unsupported in API v2 for POST and PUT requests. Please use 'Content-Type: application/json'."}
}


Example script:
~~~
#!/usr/bin/env python2

import requests
import json

SATELLITE = 'satellite.example.com'
HEADERS = {'content-type': 'application/json'}
URL = 'http://' + SATELLITE + '/api/v2/hosts/78'
DATA = json.dumps({
  "host": {
    "managed": "false"
  }
})

r = requests.put(URL, auth=('admin', 'p@$$w0rd'), headers=HEADERS, data=DATA)
print r.text
~~~


production.log shows:
~~~
2018-11-30T18:26:07 [I|app|] Started PUT "/api/v2/hosts/78" for 172.21.0.254 at 2018-11-30 18:26:07 -0200
2018-11-30T18:26:07 [I|app|09545] Processing by Api::V2::HostsController#update as JSON
2018-11-30T18:26:07 [I|app|09545]   Parameters: {"host"=>{"managed"=>"false"}, "apiv"=>"v2", "id"=>"78"}
2018-11-30T18:26:07 [I|app|09545] Redirected to https://satellite.example.com/api/v2/hosts/78
2018-11-30T18:26:07 [I|app|09545] Filter chain halted as #<Proc:0x00000000087ccf60@/opt/theforeman/tfm-ror51/root/usr/share/gems/gems/actionpack-5.1.6/lib/act
ion_controller/metal/force_ssl.rb:65> rendered or redirected
2018-11-30T18:26:07 [I|app|09545] Completed 301 Moved Permanently in 1ms (ActiveRecord: 0.0ms)
2018-11-30T18:26:08 [I|app|] Started PUT "/api/v2/hosts/78" for 172.21.0.254 at 2018-11-30 18:26:08 -0200
2018-11-30T18:26:08 [I|app|436da] Processing by Api::V2::HostsController#update as JSON
2018-11-30T18:26:08 [I|app|436da]   Parameters: {"apiv"=>"v2", "id"=>"78"}
2018-11-30T18:26:08 [I|app|436da] Current user: foreman_admin (administrator)
2018-11-30T18:26:08 [I|app|436da] Authorized user admin(Admin User)
2018-11-30T18:26:08 [I|app|436da] Current user: admin (administrator)
2018-11-30T18:26:08 [I|app|436da]   Rendering api/v2/errors/unsupported_content_type.json.rabl within api/v2/layouts/error_layout
2018-11-30T18:26:08 [I|app|436da]   Rendered api/v2/errors/unsupported_content_type.json.rabl within api/v2/layouts/error_layout (1.3ms)
2018-11-30T18:26:08 [I|app|436da] Filter chain halted as :check_content_type rendered or redirected
2018-11-30T18:26:08 [I|app|436da] Completed 415 Unsupported Media Type in 51ms (Views: 6.8ms | ActiveRecord: 19.2ms)
~~~


Version-Release number of selected component (if applicable):
Satellite 6.4.0 but also applies to 6.3.5 and likely older versions as well.

How reproducible:
Every time.
This issue only affects PUT requests. GET and DELETE requests are successfully redirected to https without losing the content-type header value.

Steps to Reproduce:
1. Run the script above

Actual results:
The script fails to run, Satellite sends error message stating 'content-type' header is empty when it's actually not.

Expected results:
The script should run, or the error message should make it clear that API calls need to use HTTPS only.

Additional info: