CMake: colorised through test -t doesn't work

CMakeModules/CMakeColors.cmake

@@ -1,8 +1,13 @@
 if(NOT WIN32)
-  # [ -t 2 ] tests whether stderr is interactive.
-  # The negation '!' is because for POSIX shells, 0 is true and 1 is false.
-  execute_process(COMMAND test ! -t 2 RESULT_VARIABLE IS_STDERR_INTERACTIVE)
-  if(IS_STDERR_INTERACTIVE)
+  set(_use_color ON)
+  if("0" STREQUAL "$ENV{CLICOLOR}")
+    set(_use_color OFF)
+  endif()
+  if("0" STREQUAL "$ENV{CLICOLOR_FORCE}")
+    set(_use_color OFF)
+  endif()
+
+  if(_use_color)
     string(ASCII 27 Esc)
     set(ColorReset  "${Esc}[m")
     set(ColorBold   "${Esc}[1m")
@@ -20,5 +25,5 @@ if(NOT WIN32)
     set(BoldMagenta "${Esc}[1;35m")
     set(BoldCyan    "${Esc}[1;36m")
     set(BoldWhite   "${Esc}[1;37m")
-  endif(IS_STDERR_INTERACTIVE)
+  endif()
 endif()