fix: decode string to string

github-close-issue:  2505

Author: owl-from-hogvarts

gyp/pylib/gyp/easy_xml.py

@@ -123,10 +123,10 @@ def WriteXmlIfChanged(content, path, encoding="utf-8", pretty=False,
 
     default_encoding = locale.getdefaultlocale()[1]
     if default_encoding and default_encoding.upper() != encoding.upper():
-        if sys.platform == "win32" and sys.version_info < (3, 7):
-            xml_string = xml_string.decode("cp1251").encode(encoding)
-        else:
-            xml_string = xml_string.encode(encoding)
+        if sys.platform == "win32":
+            if isinstance(xml_string, str):
+                xml_string = xml_string.decode("cp1251")  # str --> bytes
+            xml_string = xml_string.encode(encoding)  # bytes --> str
 
     # Get the old content
     try: