On the road to (GNU) debbugs support, some blockers

[Jelle Licht <jlicht@fsfe.org>]

Thanks for working on piem, and sharing it under a free license!

In getting some local hacks set up, I ran into some inconsistencies and
issues, which may very well be misunderstandings on my part.

The first one:
the public-inbox-config man page (`man 5 public-inbox-config') demonstrates a
url without trailing '/'. Piem's documentation uses an url with trailing '/'.

It seems `piem-b4--get-am-files' assumes this url always has a trailing
'/', which makes it not work for the examples used in the
public-inbox-config manpage (and in particular, my pre-existing
configuration). I'm not unsure if public inbox supports the trailing
'/', but I see no reason to assume it would not.

The second issue; in order to map (GNU) debbugs data to inbox
configurations, the current best way I've worked out is to use the
X-GNU-PR-Package header. 

Concretely, I've had to adjust `piem-gnus-get-inbox' to also take this
particular mail header into account when trying to find matching
configured inboxes. I am not aware of a way for debbugs users to be able
to use this, without messing with non-debbugs users of gnus. Advice
appreciated.

NB, I also added the `:gnu-pr-package' to my configured piem inboxes so
the matching could take place in the first place, of course, but this is
already possible with via {setq,Customize system,$HOME.public-inbox/config}.

Third issue:

The `piem-gnus-mid-to-thread' seems to prepend a line like: "From
mboxrd@z Thu Jan 1 00:00:00 1970" to entries. The issue comes up when we
already have a line that starts with "From " at the top, which after
running the `replace-regexp-in-string' boils down to something like in
my generated m-piem file:
--8<---------------cut here---------------start------------->8---
From mboxrd@z Thu Jan  1 00:00:00 1970
>From unknown Sat May 27 07:31:53 2023
[rest of file]
--8<---------------cut here---------------end--------------->8---

AFAIK, b4 am can't deal with this, as the "From " line needs to be the
first line, and any later lines need to be parsed as email header (which
">From ..." is not). Any solutions appreciated, that (again) don't
impact non-debbugs users of gnus. My local current hack changed the
format string "From mboxrd@z Thu Jan 1 00:00:00 1970\n%s\n" by "%s\n",
and the regex from "^>*From " into "^>+From", but this will of course
break if any of the mails I'm working with contains a line starting with
"From ".

Thanks for any help, and please let me know if you'd be interested
patches for a (clean) integration with (GNU) debbugs.

Kind regards,
Jelle Licht