From: Junio C Hamano <gitster@pobox.com>
Date: Thu, 23 Oct 2014 17:02:02 +0000 (-0700)
Subject: diff -B -M: fix output for "copy and then rewrite" case
X-Git-Tag: v2.3.0-rc0~29^2
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/6936b5859c47b826437218fbfc0e2bc0935f7136?hp=6936b5859c47b826437218fbfc0e2bc0935f7136

diff -B -M: fix output for "copy and then rewrite" case

Starting from a single file, A, if you create B as a copy of A (and
possibly make some edit) and then make extensive change to A, you
will see:

$ git diff -C --name-status
C89    A    B
M      A

which is expected.  However, if you ask the same question in a
different way, you see this:

$ git diff -B -M --name-status
R89    A    B
M100   A

telling us that A was rename-edited into B (as if "A will no longer
exist as the result") and at the same time A itself was extensively
edited.

In this case, because the resulting tree still does have file A
(even if it has contents vastly different from the original), we
should use "C"opy, not "R"ename, to avoid hinting that A somehow
goes away.

Two existing tests were depending on the wrong behaviour, and fixed.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
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