bug#57400: 29.0.50; Support sending patches from VC directly

[Philip Kaludercic]

Eli Zaretskii <eliz@gnu.org> writes:

>> Cc: 57400@debbugs.gnu.org, Antoine Kalmbach <ane@iki.fi>
>> From: Lars Ingebrigtsen <larsi@gnus.org>
>> Date: Mon, 03 Oct 2022 21:06:57 +0200
>> 
>> Do many other VCs have commands to prepare patches like this?
>
> Hg and bzr do have such commands.
         ^

As I mentioned before, I have never used Bazaar before so I downloaded a
repository to test out how patches are created and the output I get when
picking out some revision is as follows:

--8<---------------cut here---------------start------------->8---
rhea$ brz send --revision 6438 -o -
Using saved parent location "http://bazaar.launchpad.net/~bzr-pqm/bzr/bzr.dev/"; 
to determine what changes to submit.
Bundling 0 revisions.
# Bazaar merge directive format 2 (Bazaar 0.90)
# revision_id: pqm@pqm.ubuntu.com-20120116142737-incpbjom3tqo3hdb
# target_branch: http://bazaar.launchpad.net/~bzr-pqm/bzr/bzr.dev/
# testament_sha1: 0363416e18dfbea56a231638540b5f10be10c81c
# timestamp: 2022-10-04 21:13:18 +0200
# base_revision_id: pqm@pqm.ubuntu.com-20120116142737-incpbjom3tqo3hdb
# 
# Begin patch
# Begin bundle
IyBCYXphYXIgcmV2aXNpb24gYnVuZGxlIHY0CiMKQlpoOTFBWSZTWdjgvvgAABJfgAAQQGFxUBIAAACv794QIABkRTaajamQyGjTaRiFGgBMBBkwQhDmaVnH5r9hMFQyJ7EUzThiw4Ixc/mQVpexbPS29yLLTxaFbWvXcN2zcydOQxpD652acQC4g4Z96jI5BipgKAAiM5Zz45Kd/4u5IpwoSGxwX3wA
--8<---------------cut here---------------end--------------->8---

Which doesn't look like a patch to me.  My understanding from[0] is that
this is a "merge directive" indicating what change has to be made.  But
according to [1] a merge directive

> [...] provides many things needed for requesting merges:

> - A machine-readable description of the merge to perform
> - An optional patch that is a preview of the changes requested
> - An optional bundle of revision data, so that the changes can be applied 
> directly from the merge directive, without retrieving data from a branch.

so it might just be that my command is wrong?

[0] 
http://doc.bazaar.canonical.com/latest/en/user-guide/sending_changes.html#creating-a-merge-directive
[1] http://doc.bazaar.canonical.com/latest/en/user-reference/send-help.html