use IPC::Run qw(run);

    my $branch;

        die if ! -d $clonePath;
        $branch = `(cd $clonePath; hg log --template '{branch}' -r $rev2)`;
        $diff .= `(cd $clonePath; hg log -r $rev1 -r $rev2 -b $branch)`;
        $diff .= `(cd $clonePath; hg diff -r $rev1:$rev2)`;

        die "repository '$uri' is not in the SCM cache\n" if ! -d $clonePath;
        my $out;
        run(["hg", "log", "-R", $clonePath, "-r", "reverse($rev1::$rev2) and not($rev1)"], \undef, \$out)
            or die "hg log failed";
        $diff .= $out;
        run(["hg", "diff", "-R", $clonePath, "-r", "$rev1::$rev2"], \undef, \$out)
            or die "hg diff failed";
        $diff .= $out;