Update lib/net/http/generic_request.rb

Co-authored-by: Sorah Fukumori <sora134@gmail.com>

Author: taketo1113

lib/net/http/generic_request.rb

@@ -52,9 +52,7 @@ def initialize(m, reqbody, resbody, uri_or_path, initheader = nil) # :nodoc:
     initialize_http_header initheader
     self['Accept'] ||= '*/*'
     self['User-Agent'] ||= 'Ruby'
-    host = @host.dup
-    host << ":" << @port.to_s if @port
-    self['Host'] ||= "#{host}" if host
+    self['Host'] ||= @port ? "#{@host}:#{@port}" : @host if @host
     @body = nil
     @body_stream = nil
     @body_data = nil