Before introduction of new --diff-merges options, --first-parent
implicitly changed the default diff format for merge commits to
showing only the diff with respect to the first parent, and there were
no way to get such format from "git log" without affecting history
traversal logic that --first-parent causes.

Now, after introduction of the --diff-merges=first-parent, the
--first-parent simply implies the former, and this patch corrects
documentation accordingly.

Signed-off-by: Sergey Organov <redacted>
---
 Documentation/rev-list-options.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index 002379056a07..ded383e62ae5 100644
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt

@@ -129,6 +129,9 @@ parents) and `--max-parents=-1` (negative numbers denote no upper limit).
 	adjusting to updated upstream from time to time, and
 	this option allows you to ignore the individual commits
 	brought in to your history by such a merge.
+ifdef::git-log[]
+	Implies `--diff-merges=first-parent`.
+endif::git-log[]
 
 --not::
 	Reverses the meaning of the '{caret}' prefix (or lack thereof)

-- 
2.25.1