-open IN, '-|', 'git status' or die $!;
-my $status = join('', <IN>);
-close IN;
-die "The checkout is not clean:\n", $status unless $status =~ /\nnothing to commit \(working directory clean\)/;
-die "The checkout is not on the $master_branch branch.\n" unless $status =~ /^# On branch $master_branch\n/;
-