Don't present the user with spurious errors when overwriting a disk with a deleted, but uncommitted, gpart.
Don't present the user with spurious errors when overwriting a disk with
a deleted, but uncommitted, gpart.

Reported by:	brucec

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