Changing source does not trigger compilation

Here is how I built my package:

> python setup.py bdist_wheel --build-type RelWithDebInfo -j 4 -- -DVTK_Group_Web=ON -DVTK_SOURCE_DIR="c:/Work/VTK/VTK"

Then if I change files within c:/Work/VTK/VTK, the package is not re-built, simply installed.

Start with setup.py and reproduce the issue using the reported bdist_wheel command and VTK source path. Trace how source changes are detected between package builds; done means changing files in c:/Work/VTK/VTK causes the package to compile again instead of only being installed.

Written by the indexing model from the issue text.