(fix) newdracut.sh: define initial number for 'patch 0'

otherwise last patch number is undefined and this fails the script.

Related: rhbz#2066816

newdracut.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/bash
 
 bash -n "$0" || exit 1
 shopt -s extglob
@@ -30,6 +30,7 @@ cp dracut.spec dracut.spec.old
 
 rm *.patch; git reset --hard HEAD
 last_patch_nr=$(patchnr *.patch | sort -n | tail -n 1)
+last_patch_nr=${last_patch_nr:-0000}
 #for i in *.patch; do git rm -f $i;done
 
 if rpm -ivh --define "_srcrpmdir $PWD" --define "_specdir $PWD" --define "_sourcedir $PWD" "$srcrpm"; then