Skyscanner API ISO-3166-1 Alpha 3 code problem

skyscanner.py

# The following snippet DOES NOT work

import requests
import datetime


tomorrow = datetime.date.today() + datetime.timedelta(days=1)

api_key = "YOUR-API-KEY-HERE"

url = "http://api.skyscanner.net/apiservices/pricing/v1.0/"

headers = {
   "content-type": "application/x-www-form-urlencoded; charset=UTF-8",
   "Accept": "application/json"
}

payload = {
    "apiKey": api_key,
    "country": "GER",
    "currency": "EUR",
    "locale": "en-US",
    "originplace": "BRU",
    "destinationplace": "MAD",
    "outbounddate": str(tomorrow),
    "adults": 1,
    "locationschema": "Iata",

}

r = requests.post(url, headers=headers, data=payload)

print r.status_code
print r.text
print r.headers




# The following snippet DOES work

import requests
import datetime


tomorrow = datetime.date.today() + datetime.timedelta(days=1)

api_key = "YOUR-API-KEY-HERE"

url = "http://api.skyscanner.net/apiservices/pricing/v1.0/"

headers = {
   "content-type": "application/x-www-form-urlencoded; charset=UTF-8",
   "Accept": "application/json"
}

payload = {
    "apiKey": api_key,
    "country": "DE",
    "currency": "EUR",
    "locale": "en-US",
    "originplace": "BRU",
    "destinationplace": "MAD",
    "outbounddate": str(tomorrow),
    "adults": 1,
    "locationschema": "Iata",

}

r = requests.post(url, headers=headers, data=payload)

print r.status_code
print r.text
print r.headers

ISO-3166-1 alpha 3 codes are not accepted and the API will return 500 Internal Server Error.
ISO-3166-1 alpha 2 codes are accepted.