diff --git a/contrib/check-code.py b/contrib/check-code.py
--- a/contrib/check-code.py
+++ b/contrib/check-code.py
@@ -118,6 +118,9 @@ pypats = [
      "linebreak after :"),
     (r'class\s[^(]:', "old-style class, use class foo(object)"),
     (r'^\s+del\(', "del isn't a function"),
+    (r'\band\(', "and isn't a function"),
+    (r'\bor\(', "or isn't a function"),
+    (r'\bnot\(', "not isn't a function"),
     (r'^\s+except\(', "except isn't a function"),
     (r',]', "unneeded trailing ',' in list"),
 #    (r'class\s[A-Z][^\(]*\((?!Exception)',
diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -1120,7 +1120,7 @@ def debugpushkey(ui, repopath, namespace
         key, old, new = keyinfo
         r = target.pushkey(namespace, key, old, new)
         ui.status(str(r) + '\n')
-        return not(r)
+        return not r
     else:
         for k, v in target.listkeys(namespace).iteritems():
             ui.write("%s\t%s\n" % (k.encode('string-escape'),
diff --git a/mercurial/demandimport.py b/mercurial/demandimport.py
--- a/mercurial/demandimport.py
+++ b/mercurial/demandimport.py
@@ -111,7 +111,7 @@ def _demandimport(name, globals=None, lo
             mod = getattr(mod, comp)
         for x in fromlist:
             # set requested submodules for demand load
-            if not(hasattr(mod, x)):
+            if not hasattr(mod, x):
                 setattr(mod, x, _demandmod(x, mod.__dict__, locals))
         return mod