Response protocol should only be a single value. (#162)

Author: ioquatix

lib/async/http/protocol/http1/response.rb

@@ -31,7 +31,8 @@ def initialize(connection, version, status, reason, headers, body)
 						@connection = connection
 						@reason = reason
 
-						protocol = headers.delete(UPGRADE)
+						# Technically, there should never be more than one value for the upgrade header, but we'll just take the first one to avoid complexity.
+						protocol = headers.delete(UPGRADE)&.first
 
 						super(version, status, headers, body, protocol)
 					end