Leave empty locale unchanged when normalising

calendarweek/util.py

@@ -4,9 +4,10 @@ from typing import Optional
 
 def normalise_locale(loc: str, enc: Optional[str] = None) -> str:
     loc = locale_alias.get(loc, loc)
-    if enc:
-        enc = locale_encoding_alias.get(enc.replace("-", ""), enc)
-    else:
-        enc = getpreferredencoding()
-    loc = loc.split(".")[0] + "." + enc
+    if loc:
+        if enc:
+            enc = locale_encoding_alias.get(enc.replace("-", ""), enc)
+        else:
+            enc = getpreferredencoding()
+        loc = loc.split(".")[0] + "." + enc
     return loc