expanduser: normpath paths coming from env vars

This makes sure we get the same paths as with related functions in pathlib.

Lib/ntpath.py

@@ -379,7 +379,7 @@ def expanduser(path):
     if 'USERPROFILE' in os.environ:
         userhome = os.environ['USERPROFILE']
     elif not 'HOMEPATH' in os.environ:
-        return path
+        return os.path.normpath(path)
     else:
         try:
             drive = os.environ['HOMEDRIVE']
@@ -406,7 +406,7 @@ def expanduser(path):
     if isinstance(path, bytes):
         userhome = os.fsencode(userhome)
 
-    return userhome + path[i:]
+    return os.path.normpath(userhome) + path[i:]
 
 
 # Expand paths containing shell variable substitutions.