[release-branch.go1.7] path/filepath: handle ".." in normalizing a path on Windows
Current code assumes there are not ".." in the Clean(path).
That's not true. Clean doesn't handle leading "..", so we need to stop
normalization if we see "..".
Fixes #16793
Change-Id: I0a7901bedac17f1210b134d593ebd9f5e8483775
Reviewed-on: https://go-review.googlesource.com/27410 Reviewed-by: Ian Lance Taylor <iant@golang.org> Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-on: https://go-review.googlesource.com/28641 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>