cannot build if cloned as submodule

[umlaeute]

I just tried using Servus as a git submodule, but CMake happily refuses to configure with:

CMake Error: Could not open file for write in copy operation .../Servus/.git/hooks/pre-commit.tmp
CMake Error: : System Error: Not a directory
CMake Error at CMake/common/GitHooks.cmake:18 (configure_file):
  configure_file Problem configuring file
Call Stack (most recent call first):
  CMake/common/Common.cmake:152 (include)
  CMakeLists.txt:35 (include)

and indeed: Servus/.git is not a directory, but is a file, referencing the parent repository.

I figure this is actually a problem in https://github.com/Eyescale/CMake