fix shbang

images/macos/provision/assets/select-xamarin-sdk.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/bash -e -o pipefail
 if [ -z "$1" ]; then
   echo "No Xamarin SDK specified."
   exit 0
@@ -19,4 +19,4 @@ do
     echo "Set Current folder for ${FOLDER}"
     sudo rm -f ${FOLDER}/Current
     sudo ln -s ${FOLDER}/${XAMARIN_SDK} ${FOLDER}/Current
-done
+done