Can anyone explain why the @options array in the following code snippet doesn't gobble up the empty field at the end?

my $str = "foo:bar:";

my( $a, @options ) = split /:/, $str;
my( $b, $c, $d )   = split /:/, $str;

use Data::Dumper;
print Dumper( [ $a, \@options ] );
print Dumper( [ $b, $c, $d ] );
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$VAR1 = [
          'foo',
          [
            'bar'
          ]
        ];
$VAR1 = [
          'foo',
          'bar',
          ''
        ];
[download]

This seems to have to do with split(), as

my( $a, @options ) = ( "foo", "bar", "" );
my( $b, $c, $d )   = ( "foo", "bar", "" );

use Data::Dumper;
print Dumper( [ $a, \@options ] );
print Dumper( [ $b, $c, $d ] );
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gobbles up everything correctly:

$VAR1 = [
          'foo',
          [
            'bar',
            ''
          ]
        ];
$VAR1 = [
          'foo',
          'bar',
          ''
        ];
[download]