Index: os-prober/common.sh
===================================================================
--- os-prober.orig/common.sh
+++ os-prober/common.sh
@@ -336,3 +336,12 @@ linux_mount_boot () {
 
 	mountboot="$bootpart $mounted"
 }
+
+umount() {
+	if ! command umount $@ 2> /dev/null; then
+		error "umount error, retrying after 1 sec"
+		sleep 1
+		command umount $@
+	fi
+}
+