tests: try with commit-graph

Git 2.24.0 enabled commit-graph by default and caused crashes without
necessary update. Let's test to work with commit-graph.

Signed-off-by: Christian Hesse <mail@eworm.de>

tests/setup.sh

@@ -80,13 +80,17 @@ mkrepo() {
 			git commit -m "commit $n"
 			n=$(expr $n + 1)
 		done
-		if test "$3" = "testplus"
-		then
+		case "$3" in
+		testplus)
 			echo "hello" >a+b
 			git add a+b
 			git commit -m "add a+b"
 			git branch "1+2"
-		fi
+			;;
+		commit-graph)
+			git commit-graph write
+			;;
+		esac
 	)
 }
 
@@ -95,7 +99,7 @@ setup_repos()
 	rm -rf cache
 	mkdir -p cache
 	mkrepo repos/foo 5 >/dev/null
-	mkrepo repos/bar 50 >/dev/null
+	mkrepo repos/bar 50 commit-graph >/dev/null
 	mkrepo repos/foo+bar 10 testplus >/dev/null
 	mkrepo "repos/with space" 2 >/dev/null
 	mkrepo repos/filter 5 testplus >/dev/null