bug#27029: 26.0.50; gnus & utf are suddenly broken

[Eli Zaretskii]

> From: Sam Steingold <sds@gnu.org>
> Date: Mon, 22 May 2017 17:24:17 -0400
> 
> sorry, the last time I rebuild emacs was
> 
> May 15 10:03

Then I suspect this commit:

  commit e7b9a6fc4adc584b1c89a8e7502734d063fab2cd
  Author:     Stefan Monnier <monnier@iro.umontreal.ca>
  AuthorDate: Sun May 21 23:18:58 2017 -0400
  Commit:     Stefan Monnier <monnier@iro.umontreal.ca>
  CommitDate: Sun May 21 23:18:58 2017 -0400

      * lisp/mail/rfc2047.el: Use cl-lib & lexical-binding, silence warning

      (rfc2047-decode-encoded-words): Use dolist.
      (rfc2047-decode-string): Avoid string-to-multibyte.
      (rfc2047-pad-base64): Use pcase.