Ignore Content-Length from env.request_headers

Author: pilaf

lib/async/http/faraday/adapter.rb

@@ -111,7 +111,7 @@ def self.setup_parallel_manager(**options)
 					SocketError
 				].freeze
 
-				# Create a Farady compatible adapter.
+				# Create a Faraday compatible adapter.
 				# 
 				# @parameter timeout [Integer] The timeout for requests.
 				# @parameter options [Hash] Additional options to pass to the underlying Async::HTTP::Client.
@@ -181,6 +181,12 @@ def perform_request(env)
 						end
 
 						if headers = env.request_headers
+              # Ignore Content-Length if given, it will be set for us later anyway (lowercased)
+              if headers.has_key?("Content-Length")
+                headers = headers.dup
+                headers.delete("Content-Length")
+              end
+              
 							headers = ::Protocol::HTTP::Headers[headers]
 						end