Description of problem:
389-admin is improperly using the cgi module. When using a
multithreaded MPM (worker), mod_cgid had to be used. It happens that
389-admin needs apache (with worker MPM) and mod_cgi (and not
mod_cgid fork() itself from the main httpd process while mod_cgi
doesn't. That's why password_pipe() works fine with the latter.
Closing this bug since we moved to the ticket system: