Patrick Steinhardt [off-list ref] wrote:

We're about to extend our documentation to recommend b4 for sending
patch series ot the mailing list. Prepare for this by introducing a b4

s/ot/to/

configuration so that the tool knows to honor our preferences. For now,
this configuration does two things:

  - It configures "send-same-thread = shallow", which tells b4 to always
    send subsequent versions of the same patch series as a reply to the
    cover letter of the first version.

Huh?  Doesn't MyFirstContribution speak *against* shallow threading?

	        [...]  make sure to replace it with the correct Message-ID for your
	**previous cover letter** - that is, if you're sending v2, use the Message-ID
	from v1; if you're sending v3, use the Message-ID from v2.

Besides, GitGitGadget also employs that kind of nested threading, if I'm
not mistaken.

Thanks.