Do not rebuild when nitpick mode has been changed.

sphinx/config.py

@@ -84,8 +84,8 @@ class Config(object):
         primary_domain = ('py', 'env', [NoneType]),
         needs_sphinx = (None, None, string_classes),
         needs_extensions = ({}, None),
-        nitpicky = (False, 'env'),
-        nitpick_ignore = ([], 'html'),
+        nitpicky = (False, None),
+        nitpick_ignore = ([], None),
         numfig = (False, 'env'),
         numfig_secnum_depth = (1, 'env'),
         numfig_format = ({'figure': l_('Fig. %s'),