o Remove the race between stat(2) & fopen(3) when creating
a unique file.
o Improve bound checking when generating a unique name from
a given pathname.
o Ignore REST marker on APPE. No RFC specifies this case,
but the idea of resuming APPE's implies this.
o By default, deny upload resumes and appends by anonymous users.
Previously these commands were translated to STOU silently,
which led to broken files on server without any notification
to the user.
o Add an option, -m, to allow anonymous users to modify
existing files (e.g., to resume uploads) if filesystem
permissions permit.
Portions obrainded from: OpenBSD
MFC after: 3 weeks
a117c34534