zip: in TestVCS, skip instead of failing after VCS error

The underlying package doesn't interact with VCS. The test just does
this to simulate what the go command does. A VCS failure indicates a
problem with the test environment, not with the code being tested.

Fixes golang/go#38466

Change-Id: I1c36f7c9c644b22e01fa073a5d8a58c9a3893145
Reviewed-on: https://go-review.googlesource.com/c/mod/+/228397
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
1 file changed