LocalPath() should be used in error messages, but never when actually
trying to access a path.

Bug: 1127507
Change-Id: I03ec5421891ac67a8620cd3c7e88c2de1811e914
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2418914Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>
Auto-Submit: Andrew Grieve <agrieve@chromium.org>