Thread.CurrentPrincipal is reset in ProvideFault method of IErrorHandler

Question

I'm running into a weird problem with Thread.CurrentPrincipal. I implemented my own custom IAuthorizationPolicy in WCF. In Evaluate() method, I set evaluateContext.Properties["Principal"] = <my custom principal>. I can see that later on my Thread.CurrentPrincipal correctly contains my custom principal. The problem that I'm running into is that when I check Thread.CurrentPrincipal in ProvideFault() method of a class that implements IErrorHandler interface (this is for logging my WCF exceptions), it's somehow reset back generic principal. Now I thought that ProvideFault runs on the same thread, so why in a world is Thread.CurrentPrincipal is suddenly reset?

Thanks in advance,

Eric