From 34454e858d2a648b0a6ce56acd9def84bd2a8712 Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Date: Mon, 17 Dec 2007 21:01:25 +0000
Subject: [PATCH] rebase -p -i: handle "no changes" gracefully

Since commit 376ccb8cbb453343998e734d8a1ce79f57a4e092 (rebase -i: style
fixes and minor cleanups), unchanged SHA-1s are no longer mapped via
$REWRITTEN.  But the updating phase was not prepared for the old head
not being rewritten.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 git-rebase--interactive.sh    | 7 ++++++-
 t/t3404-rebase-interactive.sh | 6 ++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index f83e00fe8f..cd7e43faeb 100755
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -322,7 +322,12 @@ do_next () {
 		test -f "$DOTEST"/current-commit &&
 			current_commit=$(cat "$DOTEST"/current-commit) &&
 			git rev-parse HEAD > "$REWRITTEN"/$current_commit
-		NEWHEAD=$(cat "$REWRITTEN"/$OLDHEAD)
+		if test -f "$REWRITTEN"/$OLDHEAD
+		then
+			NEWHEAD=$(cat "$REWRITTEN"/$OLDHEAD)
+		else
+			NEWHEAD=$OLDHEAD
+		fi
 	else
 		NEWHEAD=$(git rev-parse HEAD)
 	fi &&
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 907c7f9f6b..74a7eb30f8 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -184,6 +184,12 @@ test_expect_success 'retain authorship when squashing' '
 	git show HEAD | grep "^Author: Twerp Snog"
 '
 
+test_expect_success '-p handles "no changes" gracefully' '
+	HEAD=$(git rev-parse HEAD) &&
+	git rebase -i -p HEAD^ &&
+	test $HEAD = $(git rev-parse HEAD)
+'
+
 test_expect_success 'preserve merges with -p' '
 	git checkout -b to-be-preserved master^ &&
 	: > unrelated-file &&