Routes seemingly disappear on .NET 4.5.1 with default configuration

[dotnetchris]

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I don't know how readily reproduciable this is, but on our server that we recently upgraded to .NET 4.5.1 alot of applications broke. The crux of it seems to be related to WebActivator and calls to Assembly.GetCallingAssembly()

It seems that instead of returning the My.Mvc.App assembly, it will instead return WebActivator and unsurprisingly return no routes.

I had to update applications to

routes.MapAttributeRoutes(configuration => configuration.AddRoutesFromAssemblyOf<HomeController>());