Middleware path-based mapping reapplies to PathBase on unhandled exception

[AlexAlappsis]

When adding a middleware mapping with IApplicationBuilder.Map(), the map path is reflected in HttpContext.Request.PathBase. If the application experiences an unhandled exception, and the IApplicationBuilder isn't setup with an exception handler(i.e. UseDeveloperExceptionPage()) the PathBase will be appended to.
So if my map is "/v1", after an unhandled exception the HttpContext.Request.PathBase will be "/v1/v1" Each unhandled exception will append the mapping.

I've set up a simple sample in a github repo here. https://github.com/AlexAlappsis/AspNetMappingError.

This is a new ASP.NET 5 Web application template that I've pared down. The important parts are in the Startup.cs. In Configure I've added a mapping with the path /v1. In ConfigureSub I've commented out the default error handling.

If you go to localhost/v1 you'll see the pathbase displayed. If you then hit localhost/v1/home/error, it will throw an exception. If you then refresh localhost/v1 you'll see it repeated. I actually saw different results depending on if you're running it in IIS Express or Kestrel. In Kestrel the duplicated pathBase will always display, in IIS Express if you refresh localhost/v1 you'll see it alternate back and forth.

[Eilon]

@Tratcher any idea on this? Is this an issue deeper down, such as in Hosting or HttpAbstractions or something?

[Tratcher]

Duplicate of aspnet/HttpAbstractions#510. Already fixed in RC2.