Unescape spaces in all paths of VTK_MATPLOTLIB_PYTHONPATH.

Missed a case the first time...

Change-Id: I96de1fb3de53088d8cdd3bbb0b132ae225a1d131
Merge topic '13826-FixPathUnescape' into master

a35193e4 Unescape spaces in all paths of VTK_MATPLOTLIB_PYTHONPATH.