t9300: factor out portable "head -c" replacement

diff --git a/git-rebase.sh b/git-rebase.sh
index 0bf41ee72b79953dbb8fdab44e275c027174f5b7..44ede367ae0e24ad80ba91608d26ad3bd4bbd8da 100755 (executable)
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -87,7 +87,10 @@ preserve_merges=
 autosquash=
 keep_empty=
 test "$(git config --bool rebase.autosquash)" = "true" && autosquash=t
-gpg_sign_opt=
+case "$(git config --bool commit.gpgsign)" in
+true)  gpg_sign_opt=-S ;;
+*)     gpg_sign_opt= ;;
+esac
 
 read_basic_state () {
        test -f "$state_dir/head-name" &&