default_pre_build &&
cd "$SOURCE_DIRECTORY" &&
seq 2 100 | while read n; do
  file="SOURCE$n"
  file="${!file}"
  [ -n "$file" ] || break
  verify_file "$n" || return 1
  case "$file" in
    (*.patch) patch -fp1 -i "$SOURCE_CACHE/$file" || return 1;;
  esac
done