debuild returns 0 on SIGINT

Binary package hint: devscripts

I call debuild inside another shell script. Most of the time in the whole script is spent in dpkg-buildpackage, called by debuild. Now if I hit ctrl+c to SIGINT the build, it stops. However, debuild happens to ignore the return value of dpkg-buildpackage in case it was terminated by a signal. The following function is responsible (around line 1337 in /usr/bin/debuild):

sub system_withecho(@) {
    print STDERR " ", join(" ", @_), "\n";
    system(@_);
    if ($?>>8) {
 fatal "@_ failed";
    }
}

Why is the condition for terminating bitshifted, and not just != 0?

I'm using devscripts 2.10.61ubuntu5 on lucid.