forcing an in-body From header

[Rasmus Villemoes <rv@rasmusvillemoes.dk>]

Hi,

Some mailing lists mangle the real From: header, making it a little hard
for maintainers to apply patches directly using 'git am'. See e.g.
https://lists.openembedded.org/g/openembedded-core/message/166515 . One
way to work around that is by having an in-body From: "header".

However, merely setting sendemail.from or format.from is not enough to
get such a header, if the value happens to be identical to the patch
author (which it would usually be). So, could we get some config knob
and/or command line switch to force an in-body from header? Then one
could set that on a per-project basis, for projects with such mailing lists.

I looked into the code, and while this is obviously just a hacky patch
to see that I found the right spot, it doesn't seem to be too hard to
implement properly.

diff --git a/pretty.c b/pretty.c
index ee6114e3f0..8b9ef6f644 100644
--- a/pretty.c
+++ b/pretty.c
@@ -503,7 +503,7 @@ void pp_user_info(struct pretty_print_context *pp,
                map_user(pp->mailmap, &mailbuf, &maillen, &namebuf,
&namelen);

        if (cmit_fmt_is_mail(pp->fmt)) {
-               if (pp->from_ident && ident_cmp(pp->from_ident, &ident)) {
+               if (pp->from_ident && (ident_cmp(pp->from_ident, &ident)
|| getenv("GIT_FORCE_BODY_FROM"))) {
                        struct strbuf buf = STRBUF_INIT;

                        strbuf_addstr(&buf, "From: ");

Thanks,
Rasmus