update_version_stamp.lua: Use NUL on Windows #11323

scripts/update_version_stamp.lua

@@ -13,6 +13,10 @@ local function die(msg)
   os.exit(0)
 end
 
+local function iswin()
+  return package.config:sub(1,1) == '\\'
+end
+
 if #arg ~= 2 then
   die(string.format("Expected two args, got %d", #arg))
 end
@@ -20,7 +24,8 @@ end
 local versiondeffile = arg[1]
 local prefix = arg[2]
 
-local described = io.popen('git describe --first-parent --dirty 2>/dev/null'):read('*l')
+local dev_null = iswin() and 'NUL' or '/dev/null'
+local described = io.popen('git describe --first-parent --dirty 2>'..dev_null):read('*l')
 if not described then
   described = io.popen('git describe --first-parent --tags --always --dirty'):read('*l')
 end