setting a git safe.directory during cmake FetchContent_MakeAvailable

tl;dr during cmake command FetchContent_MakeAvailable, an underlying git checkout tag proces fails with fatal: detected dubious ownership in repository at ...; how can I have cmake set a git safe.directory before the git checkout process?

problem

Given the following cmake commands

FetchContent_Declare(
    googletest
    GIT_REPOSITORY https://github.com/google/googletest.git
    GIT_TAG        v1.17.0
    OVERRIDE_FIND_PACKAGE
)
FetchContent_MakeAvailable(googletest)

The cmake command FetchContent_MakeAvailable runs these processes

1. git clone --no-checkout --config advice.detachedHead=false https://github.com/google/googletest.git googletest-src
2. cd googletest-src
3. git checkout v1.17.0

However the git checkout process fails with error

        Cloning into 'googletest-src'...
        warning: templates not found in /usr/share/git-core/templates
        fatal: detected dubious ownership in repository at '/mnt/c/Users/User/Project/build.Debug/_deps/googletest-src'
            To add an exception for this directory, call:

                git config --global --add safe.directory /mnt/c/Users/User/Project/build.Debug/_deps/googletest-src
        CMake Error at build.Debug/CMakeFiles/fc-tmp/googletest/googletest-gitclone.cmake:61 (message):
          Failed to checkout tag: 'v1.17.0'
        Call Stack (most recent call first):
          build.Debug/CMakeFiles/fc-tmp/googletest/download.cmake:7 (include)
          /usr/local/share/cmake-3.30/Modules/FetchContent.cmake:1753 (include)
          /usr/local/share/cmake-3.30/Modules/FetchContent.cmake:1706 (__FetchContent_doStepDirect)
          /usr/local/share/cmake-3.30/Modules/FetchContent.cmake:1607 (__FetchContent_populateDirect)
          /usr/local/share/cmake-3.30/Modules/FetchContent.cmake:2145:EVAL:2 (__FetchContent_doPopulation)
          /usr/local/share/cmake-3.30/Modules/FetchContent.cmake:2145 (cmake_language)
          /usr/local/share/cmake-3.30/Modules/FetchContent.cmake:2384 (__FetchContent_Populate)
          CMakeLists.txt:104 (FetchContent_MakeAvailable)

        -- Configuring incomplete, errors occurred!

How can I instruct cmake to set a git safe directory before the git checkout command?

This is probably occurring because the path /mnt/c/Users/User/Project/build.Debug/_deps/googletest-src is a Windows NTFS disk. But the cmake process is running in Ubuntu 24 WSL.

fix attempt #1

I added the following cmake command to call git config --add safe.directory ...

execute_process(
    COMMAND find_package(Git REQUIRED) config --global --verbose --add safe.directory "/mnt/c/Users/User/Project/build.Debug/_deps/googletest-src"
)

so the cmake commands were

FetchContent_Declare(...)
execute_process(...)
FetchContent_MakeAvailable(...)

but this did not fix the fatal error.