Fixes usage of upper case headears

Author: nunomaduro

algoliasearch/http/request_options.py

@@ -16,7 +16,7 @@ def __init__(self, headers, query_parameters, timeouts, data):
     def __setitem__(self, option, value):
         # type: (str, Any) -> None
 
-        if option in Params.HEADERS:
+        if option.upper() in [header.upper() for header in Params.HEADERS]:
             self.headers[option] = str(value)
         elif option in Params.QUERY_PARAMETERS:
             self.query_parameters[option] = value

tests/unit/http/test_request_options.py

@@ -14,7 +14,9 @@ def setUp(self):
 
             # Headers
             'User-Agent': 'foo',
-            'X-Forwarded-For': '1.1.1.1',
+
+            # Upper case header, should equal to `X-Forwarded-For`
+            'X-FORWARDED-FOR': '1.1.1.1',
 
             # Query Params
             'createIfNotExists': True,
@@ -39,7 +41,7 @@ def test_default_user_agent(self):
     def test_headers(self):
         self.assertEqual(self.request_options.headers['User-Agent'], 'foo')
         self.assertEqual(
-            self.request_options.headers['X-Forwarded-For'],
+            self.request_options.headers['X-FORWARDED-FOR'],
             '1.1.1.1'
         )