BLD: Fix has_include_file side-effect

Kojoley · Kojoley · commit ae264b104a7c · 2017-10-22T00:24:25.000+03:00
The passed argument would be modified by function while it not designed to.
diff --git a/setupext.py b/setupext.py
@@ -151,7 +151,8 @@ def has_include_file(include_dirs, filename):
     directories in `include_dirs`.
     """
     if sys.platform == 'win32':
-        include_dirs += os.environ.get('INCLUDE', '.').split(';')
+        include_dirs = list(include_dirs)
+        include_dirs += os.environ.get('INCLUDE', '.').split(os.pathsep)
     for dir in include_dirs:
         if os.path.exists(os.path.join(dir, filename)):
             return True
