R1:13275860b18e

When stopping on redirect, show a full stack trace

Summary: Ref T4140. Provide more debugging information so we can figure out what's going on with redirect loops.

Test Plan: {F83868}

Reviewers: chad, btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4140

Differential Revision: https://secure.phabricator.com/D7620