Properly forward exit 1 code from the paper root command

This is so the CI server can pick up when applying patches fails,
and mark the build as a failure.

scripts/build.sh

@@ -12,4 +12,4 @@ gitcmd="git -c commit.gpgsign=false"
 if [ "$2" == "--jar" ]; then
     mvn clean install && ./scripts/paperclip.sh "$basedir"
 fi
-)
+) || exit 1