rebase: remember strategy and strategy options

When a rebase is resumed, interactive rebase remembers any merge
strategy passed when the rebase was initated. Make non-interactive
rebase remember any merge strategy as well. Also make non-interactive
rebase remember any merge strategy options.

To be able to resume a rebase that was initiated with an older version
of git (older than this commit), make sure not to expect the saved
option files to exist.

Test case idea taken from Junio's 71fc224 (t3402: test "rebase
-s<strategy> -X<opt>", 2010-11-11).

Signed-off-by: Martin von Zweigbergk <martin.von.zweigbergk@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-rebase--interactive.sh

@@ -584,7 +584,6 @@ skip_unnecessary_picks () {
 
 get_saved_options () {
 	test -d "$rewritten" && preserve_merges=t
-	test -f "$state_dir"/strategy && strategy="$(cat "$state_dir"/strategy)"
 	test -f "$state_dir"/rebase-root && rebase_root=t
 }
 
@@ -713,7 +712,6 @@ case "$rebase_root" in
 *)
 	: >"$state_dir"/rebase-root ;;
 esac
-test -z "$strategy" || echo "$strategy" > "$state_dir"/strategy
 if test t = "$preserve_merges"
 then
 	if test -z "$rebase_root"

git-rebase.sh

@@ -81,6 +81,9 @@ read_basic_state () {
 	fi &&
 	GIT_QUIET=$(cat "$state_dir"/quiet) &&
 	test -f "$state_dir"/verbose && verbose=t
+	test -f "$state_dir"/strategy && strategy="$(cat "$state_dir"/strategy)"
+	test -f "$state_dir"/strategy_opts &&
+		strategy_opts="$(cat "$state_dir"/strategy_opts)"
 }
 
 write_basic_state () {
@@ -89,6 +92,9 @@ write_basic_state () {
 	echo "$orig_head" > "$state_dir"/orig-head &&
 	echo "$GIT_QUIET" > "$state_dir"/quiet &&
 	test t = "$verbose" && : > "$state_dir"/verbose
+	test -n "$strategy" && echo "$strategy" > "$state_dir"/strategy
+	test -n "$strategy_opts" && echo "$strategy_opts" > \
+		"$state_dir"/strategy_opts
 }
 
 output () {

t/t3418-rebase-continue.sh

@@ -45,4 +45,33 @@ test_expect_success 'rebase --continue can not be used with other options' '
 	test_must_fail git rebase --continue -v
 '
 
+test_expect_success 'rebase --continue remembers merge strategy and options' '
+	rm -fr .git/rebase-* &&
+	git reset --hard commit-new-file-F2-on-topic-branch &&
+	test_commit "commit-new-file-F3-on-topic-branch" F3 32 &&
+	test_when_finished "rm -fr test-bin funny.was.run" &&
+	mkdir test-bin &&
+	cat >test-bin/git-merge-funny <<-EOF
+	#!$SHELL_PATH
+	case "\$1" in --opt) ;; *) exit 2 ;; esac
+	shift &&
+	>funny.was.run &&
+	exec git merge-recursive "\$@"
+	EOF
+	chmod +x test-bin/git-merge-funny &&
+	(
+		PATH=./test-bin:$PATH
+		test_must_fail git rebase -s funny -Xopt master topic
+	) &&
+	test -f funny.was.run &&
+	rm funny.was.run &&
+	echo "Resolved" >F2 &&
+	git add F2 &&
+	(
+		PATH=./test-bin:$PATH
+		git rebase --continue
+	) &&
+	test -f funny.was.run
+'
+
 test_done