URL Rewrite Module causes exception on 303 and 307 redirects (since Response.RedirectLocation is null)

Steps to reproduce

Below exception noticed when testing OWIN Google authentication.

Server Error in '/' Application.
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Value cannot be null.
Parameter name: input
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.ArgumentNullException: Value cannot be null.
Parameter name: input
Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. 
Stack Trace:
[ArgumentNullException: Value cannot be null.
Parameter name: input]
   System.Text.RegularExpressions.Regex.IsMatch(String input) +6654226
   EPiServer.UriSupport.IsSchemeSpecified(String uri) +38
   EPiServer.UrlBuilder.Init(String url) +57
   EPiServer.UrlBuilder..ctor(String url) +45
   EPiServer.Web.UrlRewriteModule.HttpUrlRewriteToExternal(String url, RebaseKind typeOfUrl) +94
   EPiServer.Web.UrlRewriteModuleBase.EndRequestEventHandler(Object sender, EventArgs e) +254
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +136
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +69
 

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Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.34009