once (CWD a/b/c vs. 3 CWDs). If an error occurs, we fall back to the default
method of a single CWD per directory element. Since this is technically
a violation of the basic FTP RFC, this behavior is under a compile-time
option FTP_COMBINE_CWDS and is off by default. It should work with most
Unix-based FTP daemons and can save latency.
MFC after: 2 weeks