getFile still returns a FileHandle, even if the file doesn't exist on
disk. Work-around this by checking if the file exists before adding
the file handle to the map.
Fixesgolang/go#38498
Change-Id: Ie02679068b37bf4f3d19966c6cfcf2361086b1de
Reviewed-on: https://go-review.googlesource.com/c/tools/+/242924
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>