Need to add hpp headers to valid extension when they are and aren't p…

…rovided via command line

src/roslint/cpplint.py

@@ -575,8 +575,6 @@ def ProcessHppHeadersOption(val):
   global _hpp_headers
   try:
     _hpp_headers = set(val.split(','))
-    # Automatically append to extensions list so it does not have to be set 2 times
-    _valid_extensions.update(_hpp_headers)
   except ValueError:
     PrintUsage('Header extensions must be comma separated list.')
 
@@ -6028,6 +6026,9 @@ def ProcessConfigOverrides(filename):
   for filter in reversed(cfg_filters):
      _AddFilters(filter)
 
+  # These are either the default headers or were modified above by options
+  _valid_extensions.update(_hpp_headers)
+
   return True