kdepaths is generated from src/kdepaths.py.in (in CMakeLists.txt), and when installed on windows is given an absolute path, rather than a relative one.

When doing the byte compile and install (the top change), the _basepath of kdepaths.py already includes the ${CMAKE_CURRENT_BINARY_DIR}, and this results in it trying to make a ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CURRENT_BINARY_DIR}/... directory (i.e. C:/somestuff/C:/somestuff)

When doing the file copy (the bottom change), $ENV{DESTDIR} is blank and results in it trying to copy files into /C:/... , which upsets windows.