#2503 make singletons compared with "is" not == or !=
Thanks to Wummel for the patch
diff --git a/Mac/BuildScript/build-installer.py b/Mac/BuildScript/build-installer.py
index 8bdebe6..37974e9 100755
--- a/Mac/BuildScript/build-installer.py
+++ b/Mac/BuildScript/build-installer.py
@@ -289,7 +289,7 @@
     fd = os.popen(commandline, 'r')
     data = fd.read()
     xit = fd.close()
-    if xit != None:
+    if xit is not None:
         sys.stdout.write(data)
         raise RuntimeError, "command failed: %s"%(commandline,)
 
@@ -300,7 +300,7 @@
     fd = os.popen(commandline, 'r')
     data = fd.read()
     xit = fd.close()
-    if xit != None:
+    if xit is not None:
         sys.stdout.write(data)
         raise RuntimeError, "command failed: %s"%(commandline,)