NullReferenceException in datetime analysis

[zooba]

Got the following exception while analysing test.support.init.py:1472 from CPython 3.5. Can't see any obvious way to fix it other than checking _type for null. The null is apparently coming from the days property in datetime.py:474, which apparently has not assigned a type.

Application: devenv.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.NullReferenceException
Stack:
   at Microsoft.PythonTools.Analysis.Values.BuiltinNamespace`1[[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]].GetMember(Microsoft.PythonTools.Parsing.Ast.Node, Microsoft.PythonTools.Analysis.AnalysisUnit, System.String)
   at Microsoft.PythonTools.Analysis.AnalysisSetExtensions.GetMember(Microsoft.PythonTools.Analysis.IAnalysisSet, Microsoft.PythonTools.Parsing.Ast.Node, Microsoft.PythonTools.Analysis.AnalysisUnit, System.String)
   at Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator.EvaluateMember(Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator, Microsoft.PythonTools.Parsing.Ast.Node)
   at Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator.EvaluateWorker(Microsoft.PythonTools.Parsing.Ast.Node)
   at Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator.EvaluateBinary(Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator, Microsoft.PythonTools.Parsing.Ast.Node)
   at Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator.EvaluateWorker(Microsoft.PythonTools.Parsing.Ast.Node)
   at Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator.EvaluateParenthesis(Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator, Microsoft.PythonTools.Parsing.Ast.Node)
   at Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator.EvaluateWorker(Microsoft.PythonTools.Parsing.Ast.Node)
   at Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator.EvaluateAnd(Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator, Microsoft.PythonTools.Parsing.Ast.Node)
   at Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator.EvaluateWorker(Microsoft.PythonTools.Parsing.Ast.Node)
   at Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator.EvaluateOr(Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator, Microsoft.PythonTools.Parsing.Ast.Node)
   at Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator.EvaluateWorker(Microsoft.PythonTools.Parsing.Ast.Node)
   at Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator.EvaluateParenthesis(Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator, Microsoft.PythonTools.Parsing.Ast.Node)
   at Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator.EvaluateWorker(Microsoft.PythonTools.Parsing.Ast.Node)
   at Microsoft.PythonTools.Analysis.Analyzer.DDG.Walk(Microsoft.PythonTools.Parsing.Ast.IfStatement)
   at Microsoft.PythonTools.Parsing.Ast.IfStatement.Walk(Microsoft.PythonTools.Parsing.Ast.PythonWalker)
   at Microsoft.PythonTools.Analysis.Analyzer.DDG.Walk(Microsoft.PythonTools.Parsing.Ast.SuiteStatement)
   at Microsoft.PythonTools.Parsing.Ast.SuiteStatement.Walk(Microsoft.PythonTools.Parsing.Ast.PythonWalker)
   at Microsoft.PythonTools.Analysis.Analyzer.FunctionAnalysisUnit.AnalyzeWorker(Microsoft.PythonTools.Analysis.Analyzer.DDG, System.Threading.CancellationToken)
   at Microsoft.PythonTools.Analysis.Analyzer.DDG.Analyze(Microsoft.PythonTools.Analysis.Deque`1<Microsoft.PythonTools.Analysis.AnalysisUnit>, System.Threading.CancellationToken, System.Action`1<Int32>, Int32)
   at Microsoft.PythonTools.Analysis.PythonAnalyzer.AnalyzeQueuedEntries(System.Threading.CancellationToken)
   at Microsoft.PythonTools.Intellisense.AnalysisQueue+GroupAnalysis.Analyze(System.Threading.CancellationToken)
   at Microsoft.PythonTools.Intellisense.AnalysisQueue.Worker(System.Object)
   at System.Threading.ThreadHelper.ThreadStart_Context(System.Object)
   at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)
   at System.Threading.ThreadHelper.ThreadStart(System.Object)