implement another suggestion from @junghans

set(temp_git_info "false")

if(GIT_FOUND AND EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/../.git)

  set(temp_git_info "true")

  execute_process(COMMAND ${GIT_EXECUTABLE} rev-parse HEAD

  execute_process(COMMAND ${GIT_EXECUTABLE} -C ${CMAKE_CURRENT_SOURCE_DIR}/../.git rev-parse HEAD

    OUTPUT_VARIABLE temp_git_commit

    ERROR_QUIET

    OUTPUT_STRIP_TRAILING_WHITESPACE)

  execute_process(COMMAND ${GIT_EXECUTABLE} rev-parse --abbrev-ref HEAD

  execute_process(COMMAND ${GIT_EXECUTABLE} -C ${CMAKE_CURRENT_SOURCE_DIR}/../.git rev-parse --abbrev-ref HEAD

    OUTPUT_VARIABLE temp_git_branch

    ERROR_QUIET

    OUTPUT_STRIP_TRAILING_WHITESPACE)

  execute_process(COMMAND ${GIT_EXECUTABLE} describe --dirty=-modified

  execute_process(COMMAND ${GIT_EXECUTABLE} -C ${CMAKE_CURRENT_SOURCE_DIR}/../.git describe --dirty=-modified

    OUTPUT_VARIABLE temp_git_describe

    ERROR_QUIET

    OUTPUT_STRIP_TRAILING_WHITESPACE)