Re: [PATCH v3 1/9] show, log: provide a --remerge-diff capability

+static int do_remerge_diff(struct rev_info *opt,
+			   struct commit_list *parents,
+			   struct object_id *oid,
+			   struct commit *commit)
+{
+	struct merge_options o;
+	struct commit_list *bases;
+	struct merge_result res = {0};
+	struct pretty_print_context ctx = {0};
+	struct commit *parent1 = parents->item;
+	struct commit *parent2 = parents->next->item;
+	struct strbuf parent1_desc = STRBUF_INIT;
+	struct strbuf parent2_desc = STRBUF_INIT;
+
+	/* Setup merge options */
+	init_merge_options(&o, the_repository);
+	o.show_rename_progress = 0;
+
+	ctx.abbrev = DEFAULT_ABBREV;
+	format_commit_message(parent1, "%h (%s)", &parent1_desc, &ctx);
+	format_commit_message(parent2, "%h (%s)", &parent2_desc, &ctx);
+	o.branch1 = parent1_desc.buf;
+	o.branch2 = parent2_desc.buf;
+
+	/* Parse the relevant commits and get the merge bases */
+	parse_commit_or_die(parent1);
+	parse_commit_or_die(parent2);
+	bases = get_merge_bases(parent1, parent2);

+test_description='remerge-diff handling'
+
+. ./test-lib.sh
+
+test_expect_success 'setup basic merges' '
+	test_write_lines 1 2 3 4 5 6 7 8 9 >numbers &&
+	git add numbers &&
+	git commit -m base &&
+
+	git branch feature_a &&
+	git branch feature_b &&
+	git branch feature_c &&
+
+	git branch ab_resolution &&
+	git branch bc_resolution &&
+
+	git checkout feature_a &&
+	test_write_lines 1 2 three 4 5 6 7 eight 9 >numbers &&
+	git commit -a -m change_a &&
+
+	git checkout feature_b &&
+	test_write_lines 1 2 tres 4 5 6 7 8 9 >numbers &&
+	git commit -a -m change_b &&
+
+	git checkout feature_c &&
+	test_write_lines 1 2 3 4 5 6 7 8 9 10 >numbers &&
+	git commit -a -m change_c &&
+
+	git checkout bc_resolution &&
+	git merge --ff-only feature_b &&
+	# no conflict
+	git merge feature_c &&
+
+	git checkout ab_resolution &&
+	git merge --ff-only feature_a &&
+	# conflicts!
+	test_must_fail git merge feature_b &&
+	# Resolve conflict...and make another change elsewhere
+	test_write_lines 1 2 drei 4 5 6 7 acht 9 >numbers &&
+	git add numbers &&