Handle ExcludeAncestorsOf in Gitiles fake
Handle ExcludeAncestorsOf in Gitiles fake

Once ExcludeAncestorsOf is found, Log must stop traversing the tree.

R=05bb588aa9020353543fee7ac4e6e0a3d0d6f6ed@google.com

Change-Id: Id649a49f4dd6995cc8f0519ef57b4dd8a4a61300
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/2410717
Reviewed-by: Anthony Polito <05bb588aa9020353543fee7ac4e6e0a3d0d6f6ed@google.com>
Commit-Queue: Josip Sokcevic <4606aec58cba917397ff2e4738f995e4758694f8@google.com>

luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go