GitLab

Accept more user names, since they can be
mangled badly by modern Unix mailers (e.g. Solaris 2.5 mail.local).
Be a little more picky about dates to compensate.
Match all the digits of a year, as per RFC 1123 section 5.2.14.
(rmail-nuke-pinhead-header): Adjust to regexp renumbering in
rmail-unix-mail-delimiter.