gyp: use "is" when comparing to None

PR-URL: https://github.com/nodejs/node-gyp/pull/1860
Reviewed-By: Christian Clauss <cclauss@me.com>
Reviewed-By: Rod Vagg <r@va.gg>

gyp/pylib/gyp/generator/ninja.py

@@ -726,7 +726,7 @@ class NinjaWriter(object):
           elif var == 'name':
             extra_bindings.append(('name', cygwin_munge(basename)))
           else:
-            assert var == None, repr(var)
+            assert var is None, repr(var)
 
         outputs = [self.GypPathToNinja(o, env) for o in outputs]
         if self.flavor == 'win':

gyp/pylib/gyp/generator/xcode.py

@@ -539,7 +539,7 @@ def ExpandXcodeVariables(string, expansions):
   """
 
   matches = _xcode_variable_re.findall(string)
-  if matches == None:
+  if matches is None:
     return string
 
   matches.reverse()

gyp/pylib/gyp/input.py

@@ -155,7 +155,7 @@ def GetIncludedBuildFiles(build_file_path, aux_data, included=None):
   in the list will be relative to the current directory.
   """
 
-  if included == None:
+  if included is None:
     included = []
 
   if build_file_path in included:
@@ -1062,7 +1062,7 @@ def EvalCondition(condition, conditions_key, phase, variables, build_file):
     else:
       false_dict = None
       i = i + 2
-    if result == None:
+    if result is None:
       result = EvalSingleCondition(
           cond_expr, true_dict, false_dict, phase, variables, build_file)
 
@@ -1603,7 +1603,7 @@ class DependencyGraphNode(object):
 
   def DirectDependencies(self, dependencies=None):
     """Returns a list of just direct dependencies."""
-    if dependencies == None:
+    if dependencies is None:
       dependencies = []
 
     for dependency in self.dependencies:
@@ -1631,7 +1631,7 @@ class DependencyGraphNode(object):
     public entry point.
     """
 
-    if dependencies == None:
+    if dependencies is None:
       dependencies = []
 
     index = 0