SERVER-42264 Improve SCons performance

Author: Mathew Robinson

src/third_party/scons-3.1.1/scons-local-3.1.1/SCons/Node/__init__.py

@@ -614,6 +614,7 @@ def __init__(self):
         self._func_rexists = 1
         self._func_get_contents = 0
         self._func_target_from_source = 0
+        self.ninfo = None
 
         self.clear_memoized_values()
 
@@ -1131,11 +1132,10 @@ def new_ninfo(self):
         return ninfo
 
     def get_ninfo(self):
-        try:
-            return self.ninfo
-        except AttributeError:
-            self.ninfo = self.new_ninfo()
+        if self.ninfo is not None:
             return self.ninfo
+        self.ninfo = self.new_ninfo()
+        return self.ninfo
 
     def new_binfo(self):
         binfo = self.BuildInfo()