Partially backport 0f933eb5966848d96477b5148e40ac1c3e750e22 for distro-agnostic
detection of grub-btrfs snapshot functionality.

Author: Lucio Sauer <watermanpaint@posteo.net>
--- a/timeshift-autosnap
+++ b/timeshift-autosnap
@@ -53,8 +53,12 @@ if $(get_property "deleteSnapshots" "boolean" "true") ; then
     fi
 fi;
 
-if $(get_property "updateGrub" "boolean" "true") && [ "$(pacman -Qs ^grub-btrfs$)" ]; then
-    grub-mkconfig -o /boot/grub/grub.cfg
-fi;
-
+if $(get_property "updateGrub" "boolean" "true") && [ -f /etc/grub.d/41_snapshots-btrfs ]; then
+	. /etc/default/grub-btrfs/config
+	if [ -s "${GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub-btrfs.cfg" ]; then
+		/etc/grub.d/41_snapshots-btrfs
+	else
+		${GRUB_BTRFS_MKCONFIG:-grub-mkconfig} -o ${GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub.cfg
+	fi
+fi
 exit 0