[bug-gawk] FPAT bug?

[Ed Morton]

Is this a bug?

$ cat tst.awk
BEGIN { FPAT="[^,]*" }
{
     print NF, $0
     for (i=1;i<=NF;i++)
         print "\t" i, "[" $i "]"
     print ""
}

$ cat -v file.csv
,,3
,,3

$ awk -f tst.awk file.csv
3 ,,3
        1 []
        2 []
        3 [3]

2 ,,3
        1 []
        2 [3]

Note that awk recognizes 3 fields in the first line but only 2 in the second. If 
it's not a bug - what's causing that behavior?

$ gawk --version
GNU Awk 4.1.4, API: 1.1 (GNU MPFR 3.1.5, GNU MP 6.1.2)
Copyright (C) 1989, 1991-2016 Free Software Foundation.

$ $SHELL --version
GNU bash, version 4.4.12(3)-release (x86_64-unknown-cygwin)
Copyright (C) 2016 Free Software Foundation, Inc.

Regards,

    Ed.