Externally feeding the drafts folder -- git format-patch integration

[Elias Oltmanns <eo@nebensachen.de>]

Hi there,

my question is how best to sneak externally drafted e-mails into the
gnus ecosystem in order to be able to post edit them, have them on file
after sending them off, have the registry know all about it for
splitting by parent etc. For example, I would like to smooth the way for
patch reviewal and discussion. Ideally, the work flow would look similar
to this:
1. Do some development in local git repository (using magit).
2. Generate a patch series from the local commits with a command like
   $ git format-patch --thread --cover-letter --to developer@example.org \
   --cc devel@list.example.org --stdout > ~/Mail/git.spool
3. Fire up gnus and have the patch series stored in ~/Mail/git.spool
   magically appear in the drafts group so I can edit the cover letter
   and possibly annotate some of the other messages too before sending
   the off.
4. Replies to those e-mails should go to the corresponding devel folder
   by means of gnus-registry-split-fancy-with-parent.

As you may have guessed, my setup is failing at step 3. My lain attempt
was to put the following into my .gnus.el:
(setq mail-sources
      '((file :plugged t)
	(file :path "~/Mail/git.spool" :plugged t)))
...
(setq nnmail-split-fancy
  '(| ("x-gnus-mail-source" "git.spool" "nndraft:drafts")
      ...
      (: gnus-registry-split-fancy-with-parent)
      ...
      "INBOX"))

Unfortunately, the contents git.spool ends up in a newly created (and
masked) nnml directory nndraft:drafts under ~/Mail instead of the
special drafts group. Do you have any suggestions how to achieve this or
something similar?

Thanks in advance for all hints,

Elias