if you delete work directory used for building port with multiple rm with -rf flags, all instances of rm after some time fails with:
(hsn@sanatana:pts/0):~/myports/spark% rm -rf work
rm: fts_read: No such file or directory
as i see it, rm -f should never hard fail during delete process, just ignore error (directory deleted by other process) and move on.
I think SVN r268376 (in head only) should fix this.
*** This bug has been marked as a duplicate of bug 192490 ***