Fix bug in deleting files: If two ports had the same tarball and one of them changed (or was removed from the tree) then portsnap would delete that file.  This happened earlier today when one of two empty port directories was removed.  Uniquifying the lists of needed files fixes this.
Fix bug in deleting files: If two ports had the same tarball and one of
them changed (or was removed from the tree) then portsnap would delete
that file.  This happened earlier today when one of two empty port
directories was removed.  Uniquifying the lists of needed files fixes
this.

9.2-RELEASE candidate.

MFC after:	3 days

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase