test with -z switch fails with Debian Linux

[John Moore]

To the Bash Developers:

    I'm not sure if this is an issue or not, but the bash test with the -z
switch appears to be broken. This code came from the Unix Hacks book I
believe and it used to work:

        ########################################################
        # Name: ffind
        # Desc: finds files from a flat db text file
        # Args: $1 -> PATTERN - the string you want to look up
        # Vars: PATTERN, FILELIST - txt file to grep
        ########################################################

        ffind (){
        FILELIST="/root/filelist.txt"
        PATTERN="$1"
        if [ -z "PATTERN" ]; then
           echo -n "Search: "
           read PATTERN
        fi

        grep -I "$PATTERN" $FILELIST

        }

If I run the function itself without any input, it should fail the test and
prompt me for input, but it doesn't.

bash --version
GNU bash, version 3.1.17(1)-release (i486-pc-linux-gnu)
Copyright (C) 2005 Free Software Foundation, Inc.


Sincerely,

John Moore