xml2po: only write translators.xml if existing

xml2po.sh

@@ -8,6 +8,7 @@ RES=res/values
 POT=$TRAN/$PACKAGE.pot
 PODIR=translations/$PACKAGE
 PO=$PODIR/$PACKAGE-
+CREDITS=res/values/translators.xml
 
 download() {
 	FN=launchpad-$(date +%F).tar.gz
@@ -44,7 +45,7 @@ translate_po2xml() {
 		xml2po -a -l $lang -p $po $RES/strings.xml | sed "s/'/\\\\'/g" > $dir/strings.xml
 	done
 	sed -i 's/\\\\'\''/\\'\''/g' res/values-*/strings.xml
-	{
+	[ -f $CREDITS ] && {
 		cat <<EOF
 <?xml version="1.0" encoding="utf-8"?>
 <!-- AUTOGENERATED BY xml2po.sh! DO NOT CHANGE MANUALLY! -->
@@ -55,7 +56,7 @@ $(cat translations/$PACKAGE/$PACKAGE-*.po | awk -F ': | <' '/Last-Translator:/ {
 </string>
 </resources>
 EOF
-	} > res/values/translators.xml
+	} > $CREDITS
 }