sub is_safe_file {
   my $path = shift;
   stat($path) || return;    # mysteriously vaporized
   my ( $dev, $ino, $mode, $nlink, $uid, $gid ) = stat(_);

   return 0 if $uid != 0 && $uid != $<;
   return 0 if $mode & 022;
   return 1;
} ## end sub is_safe_file
[download]

On Windows 7, I'm seeing the same result as the OP.
The is_safe_file() sub returns 0, because $mode & 022 returns a true value of 18.
But the leading 0100 is ignored, and the true value of 18 is obtained simply because the 2nd and 5th bits of $mode are true.

This sub has been (in its current form) in perl5db.pl since perl-5.8.8 (maybe even earlier), and its behaviour has remained the same throughout that period.
I know buggerall about perl5db.pl and file permissions, but it feels to me that this sub should not even be called on a Windows system.

I did however find a file named simply "config_data" in a perl (not Strawberry Perl) bin folder of mine for which is_safe_file() returned true.
For that file, the value of $mode, as seen by is_safe_file(), was 33206 (0100444).
If you can set the perldb.ini permissions to that value then you might get lucky ;-)

PUCKERING, if you want to raise an issue about this with the perl developers, then create a "New Issue" at https://github.com/Perl/perl5/issues.

Cheers,
Rob