Index: os-prober-1.58/common.sh
===================================================================
--- os-prober-1.58.orig/common.sh
+++ os-prober-1.58/common.sh
@@ -313,3 +313,13 @@ linux_mount_boot () {
 
 	mountboot="$bootpart $mounted"
 }
+
+umount_exec=$(which umount)
+umount() {
+	if ! $umount_exec $@ 2> /dev/null; then
+		error "umount error, retrying after 1 sec"
+		sleep 1
+		$umount_exec $@
+	fi
+}
+