Re: [PATCH v3 2/3] patch-id: document new behaviour

[Junio C Hamano <gitster@pobox.com>]

"Michael S. Tsirkin" <mst@redhat.com> writes:

> The hash used is mostly an internal implementation detail, isn't it?

Yes, but that does not mean we can break people who keep an external
database indexed with the patch-id by changing the default under
them, and "they can give --unstable option to work it around" is a
workaround, not a fix.  Without this change, they did not have to do
anything.

I would imagine that most of these people will be using the plain
vanilla "git show" output without any ordering or hunk splitting
when coming up with such a key.  A possible way forward to allow the
configuration that corresponds to "-O<orderfile>" while not breaking
the existing users could be to make the "patch-id --stable" kick in
automatically (of course, do this only when the user did not give
the "--unstable" command line option to override) when we see the
orderfile configuration in the repository, or when we see that the
incoming patch looks like reordered (e.g. has multiple "diff --git"
header lines that refer to the same path, or the set of files
mentioned by the "diff --git" lines are not in ascending order),
perhaps?