Perl's chdir() has the unfortunate problem of being very, very, very
global. If any part of your program calls chdir() or if any library you
use calls chdir(), it changes the current working directory for the
whole program.
This is not good.
File::chdir gives you an alternative, $CWD and @CWD. These two variables
combine all the power of chdir(), File::Spec and Cwd.
