cannot correctly decode quoted-printable with CJK UTF-8 string

[tonytonyjan]

Environment:

Mail::VERSION::STRING
# => 2.7.1
RUBY_VERSION
# => 2.7.1

Reproduce:

Mail::Encodings.value_decode '=?utf-8?B?MjTmmYLplpPjgIHjg4vjg6Xjg7zjgrnjgajnlarntYTjgpLo?= =?utf-8?B?i7Hoqp7jgafkuJbnlYzjgavnmbrkv6HjgZfjgabjgYTjgb7?='
# => "24時間、ニュースと番組を���語で世界に発信していま"

Base64.decode64('MjTmmYLplpPjgIHjg4vjg6Xjg7zjgrnjgajnlarntYTjgpLoi7Hoqp7jgafkuJbnlYzjgavnmbrkv6HjgZfjgabjgYTjgb7').force_encoding('utf-8')
# => "24時間、ニュースと番組を英語で世界に発信していま"

Mail::Encodings.value_decode '=?utf-8?B?5paw5YyX5biC5pS/5bqc6K2m5a+f5bGALeS6pOmAmumBleim?= =?utf-8?B?j+aqouiIieezu+e1sWUtbWFpbOiqjeitieS/oeS7tg==?='
# => "新北市政府警察局-交通違��檢舉系統e-mail認證信件"

Base64.decode64('5paw5YyX5biC5pS/5bqc6K2m5a+f5bGALeS6pOmAmumBleimj+aqouiIieezu+e1sWUtbWFpbOiqjeitieS/oeS7tg==').force_encoding('utf-8')
# => "新北市政府警察局-交通違規檢舉系統e-mail認證信件"

related source code:

https://github.com/mikel/mail/blob/2.7.1/lib/mail/encodings.rb#L130-L137

[discdisk]

I got this problem too
#1397

[tonytonyjan]

my workaround for b-decoding:

'=?utf-8?B?MjTmmYLplpPjgIHjg4vjg6Xjg7zjgrnjgajnlarntYTjgpLo?= =?utf-8?B?i7Hoqp7jgafkuJbnlYzjgavnmbrkv6HjgZfjgabjgYTjgb7?='
  .split.map{|i| i[10..-3].unpack1('m')}.join.force_encoding('utf-8')
# => "24時間、ニュースと番組を英語で世界に発信していま"

[tonytonyjan]

moved to #1397