Regression in Windows: after 3.11.x GetRealPath doesn't respect DOS and subst mounts
C:\path is mounted as
cmSystemTools::GetRealPath("X:\file.txt") will return
C:\path\file.txt instead of
X:\file.txt as it did previously.
Reverting 640709e7 fixes the issue. Not sure what is the best solution for this, but we rely heavily on being able to mount paths as drives in Windows and this issue is blocking us to upgrade to 3.11