Avoid bug with single-part PGP/Mime

theirix requested to merge theirix/gpgit:single-part-bug into master

Some clients expect a MIME message inside an encoded PGP/Mime blob, not a plain text. Mail::GnuPG converts an incoming MIME to plain text if it is single part. It is fixed by adding an empty MIME part.

Messages created with original script failed to decrypt with the latest GPGTools (issue 48534). Patch introduces new --skip-single-part-bug option.

Merge request reports