Apparently getopt(1) for Bash is buggy, according to http://mywiki.wooledge.org/BashFAQ/035#getopts, where getopts is OK. But it's not that hard to just write scripts that don't use either of them.

bash_without_getopt_s.sh

#!/bin/bash

help() {
    echo "Bash script that parses cmd line args without getopt(s)"
    echo "Adapted from https://stackoverflow.com/questions/192249"
    echo "    -h, --help        print this help message"
    echo "    -f, --foo         set FOO variable"
    echo "    -b, --bar         set BAR variable"
    echo "    -d, --debug       enable debug (doesn't really do anything here)"
    echo "    <anything else>   becomes a positional argument"
    echo ""
    echo "Example:"
    echo "    \$ $0 -d -f 123 -b 456 abcde fghijkl"
    echo "    FOO = 123"
    echo "    BAR = 456"
    echo "    DEBUG = YES"
    echo "    \$1 = abcde"
    echo "    \$2 = fghijkl"
    echo "    \$3 = "
    echo ""
}

POSITIONAL=()
while [[ $# -gt 0 ]]
do
key="$1"
case $key in
    -h|--help)
        help
        exit 0
    ;;
    -f|--foo)
        FOO="$2"
        shift
        shift
    ;;
    -b|--bar)
        BAR="$2"
        shift
        shift
    ;;
    -d|--debug)
        DEBUG=YES
        shift
    ;;
    *)
        POSITIONAL+=("$1")
        shift
    ;;
esac
done

# positional parameters become $1, $2, $3... respectively
set -- "${POSITIONAL[@]}"

echo FOO   = "${FOO}"
echo BAR   = "${BAR}"
echo DEBUG = "${DEBUG}"
echo \$1   = "$1"
echo \$2   = "$2"
echo \$3   = "$3"