refactor: set GIT_SHA_SHORT with git command

CMakeLists.txt

@@ -32,6 +32,12 @@ set(DESKFLOW_VERSION_TWEAK 0)
 if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/.git)
   find_package(Git)
   if(GIT_FOUND)
+    execute_process(
+      COMMAND ${GIT_EXECUTABLE} rev-parse --short=8 HEAD
+      WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
+      OUTPUT_VARIABLE GIT_SHA_SHORT
+      ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE
+    )
     execute_process(
       COMMAND ${GIT_EXECUTABLE} describe --long --match v* --always
       WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"

cmake/Definitions.cmake

@@ -22,12 +22,6 @@ macro(configure_definitions)
   set(INTEG_TESTS_BIN integtests)
   set(UNIT_TESTS_BIN unittests)
 
-  if(NOT "$ENV{GIT_SHA}" STREQUAL "")
-    # Shorten the Git SHA to 8 chars for readability
-    string(SUBSTRING "$ENV{GIT_SHA}" 0 8 GIT_SHA_SHORT)
-    message(STATUS "Short Git SHA: ${GIT_SHA_SHORT}")
-  endif()
-
   if(NOT CMAKE_BUILD_TYPE STREQUAL "Debug")
     message(STATUS "Disabling debug build")
     add_definitions(-DNDEBUG)