etc: fix check_sync.py for nested namespaces

Author: james-d-mitchell

etc/check_sync.py

@@ -219,8 +219,10 @@ def _regex_pattern(args, thing: str, fn: str) -> str:
     cxx_fn = fn[:]
     fn = translate_to_py(fn)
     if is_namespace(args, thing):
-        namespace = thing.split(":")[-1]
-        pattern = f"(){namespace}_{fn}"
+        namespace = thing.split("::")
+        namespace = namespace[1:]
+        pattern = f"(){'_'.join(namespace)}_{fn}"
+        print(pattern)
     else:
         pattern = rf"(\w*){fn}"
     if not is_operator(args, thing, cxx_fn):