You could be right. We'll have to wait for devbond to tell us. Anyway, that's just as easy to calculate:

#!/usr/bin/env perl -l

use strict;
use warnings;

use Time::Piece;

my $month = 10;
my $year = 2013;

for (1 .. 7) { # Time::Piece->wday returns: Sunday = 1, ..., Saturday 
+= 7
    print +($_ - Time::Piece->strptime("$year$month" . '01', '%Y%m%d')
+->wday) % 7 + 1;
}
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Output:

6
7
1
2
3
4
5
[download]

Check:

$ cal 10 2013
    October 2013
Su Mo Tu We Th Fr Sa
       1  2  3  4  5
 6  7  8  9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30 31
[download]