#12353: argparse now correctly handles null argument values.

Patch by Torsten Landschoff.
diff --git a/Lib/argparse.py b/Lib/argparse.py
index d867611..f365385 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -1967,7 +1967,7 @@
         for arg_string in arg_strings:
 
             # for regular arguments, just add them back into the list
-            if arg_string[0] not in self.fromfile_prefix_chars:
+            if not arg_string or arg_string[0] not in self.fromfile_prefix_chars:
                 new_arg_strings.append(arg_string)
 
             # replace arguments referencing files with the file content
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index 1a5f05e..a7a4b00 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -1374,6 +1374,7 @@
         ('X @hello', NS(a=None, x='X', y=['hello world!'])),
         ('-a B @recursive Y Z', NS(a='A', x='hello world!', y=['Y', 'Z'])),
         ('X @recursive Z -a B', NS(a='B', x='X', y=['hello world!', 'Z'])),
+        (["-a", "", "X", "Y"], NS(a='', x='X', y=['Y'])),
     ]