Protocol.authenticate expects @charset to be defined

[slowjoe007]

If an error occurs during authentication (in my case the host I connect from is not permitted), the error message is attempted to be decoded.
However, at that time @charset is not yet defined:

Uncaught exception: undefined method `encoding' for nil:NilClass
	C:/Ruby/2.3.0/lib/ruby/gems/2.3.0/gems/ruby-mysql-2.9.14/lib/mysql/protocol.rb:502:in `read'
	C:/Ruby/2.3.0/lib/ruby/gems/2.3.0/gems/ruby-mysql-2.9.14/lib/mysql/protocol.rb:178:in `authenticate'
	C:/Ruby/2.3.0/lib/ruby/gems/2.3.0/gems/ruby-mysql-2.9.14/lib/mysql.rb:116:in `connect'
	C:/Ruby/2.3.0/lib/ruby/gems/2.3.0/gems/ruby-mysql-2.9.14/lib/mysql.rb:50:in `new'

ruby-mysql/lib/mysql/protocol.rb

Line 502 in 44520a1

message.force_encoding(@charset.encoding)

As you can see from the stacktrace the line in method authenticate is 178. However, @charset is not defined before line 185:

ruby-mysql/lib/mysql/protocol.rb

Lines 178 to 189 in 44520a1

	init_packet = InitialPacket.parse read
	@server_info = init_packet.server_version
	@server_version = init_packet.server_version.split(/\D/)[0,3].inject{|a,b|a.to_i*100+b.to_i}
	@thread_id = init_packet.thread_id
	client_flags = CLIENT_LONG_PASSWORD | CLIENT_LONG_FLAG | CLIENT_TRANSACTIONS | CLIENT_PROTOCOL_41 | CLIENT_SECURE_CONNECTION
	client_flags |= CLIENT_CONNECT_WITH_DB if db
	client_flags |= flag
	@charset = charset
	unless @charset
	@charset = Charset.by_number(init_packet.server_charset)
	@charset.encoding # raise error if unsupported charset
	end

I was able to help myself by modifying line 502 to:

message.force_encoding(Mysql::Charset.by_number(33).encoding)

where 33 is the numeric representation of UTF-8:

ruby-mysql/lib/mysql/charset.rb

Line 63 in 44520a1

[ 33, "utf8", "utf8_general_ci", true ],