Freshly stolen from Europe:

b() {
  setopt localoptions extendedglob

  if [[ $# -eq 1 ]]; then
    case "$1" in
      ([0-9]##)
    links "http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=$1"
    ;;
      (*@*)
        links "http://bugs.debian.org/cgi-bin/pkgreport.cgi?submitter=$1"
        ;;
      (*)
        links "http://bugs.debian.org/cgi-bin/pkgreport.cgi?pkg=${1%%_*}"
        ;;
    esac
  else
    print "$0 needs one argument"
  fi
}