Fix platform checking and env saving on Windows

CHANGELOG.md

@@ -4,6 +4,9 @@ Note: Breaking changes between versions are indicated by "💥".
 
 ## Unreleased
 
+- [Bugfix] Fix `config save` on Windows.
+- [Bugfix] Fix platform checking in user ID function
+
 ## v10.4.1 (2020-11-11)
 
 - [Bugfix] Fix dependency error during `pip install tutor` due to urllib3 incompatibility

tutor/env.py

@@ -231,7 +231,7 @@ def write_to(content, path):
     if isinstance(content, bytes):
         open_mode += "b"
     utils.ensure_file_directory_exists(path)
-    with open(path, open_mode) as of:
+    with open(path, open_mode, encoding='utf8') as of:
         of.write(content)
 
 

tutor/utils.py

@@ -130,7 +130,7 @@ def get_user_id():
     """
     Portable way to get user ID. Note: I have no idea if it actually works on windows...
     """
-    if sys.platform == "windows":
+    if sys.platform == "win32":
         return int(check_output("id", "-u").decode())
     return os.getuid()