Allow skipping of tests that depend on a modern wcwidth() via an env var

kitty_tests/parser.py

@@ -2,10 +2,11 @@
 # vim:fileencoding=utf-8
 # License: GPL v3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
 
+import os
 from functools import partial
+from unittest import skipIf
 
 from . import BaseTest
-
 from kitty.fast_data_types import parse_bytes, parse_bytes_dump, CURSOR_BLOCK
 
 
@@ -38,6 +39,7 @@ class TestParser(BaseTest):
             q.append(('draw', current))
         self.ae(tuple(q), cmds)
 
+    @skipIf('ANCIENT_WCWIDTH' in os.environ, 'wcwidth() is too old')
     def test_simple_parsing(self):
         s = self.create_screen()
         pb = partial(self.parse_bytes_dump, s)