Use an original name instead of a symlink's target path.

Fixes #20064

Change-Id: I9be3837a156bdcda0e9e065abbb425d535b27be3
Reviewed-on: https://go-review.googlesource.com/41310Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>