Fix handling of the cd command inside evaluations. It was changing PWD, which it should not do.
Fix handling of the cd command inside evaluations. It was changing PWD,
which it should not do.

PR:	12578
Reported by:	Gerald Pfeifer <pfeifer@dbai.tuwien.ac.at>
Submitted by:	Niall Smart <niall@pobox.com>

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