testdata/vcstest/bzr: fix unit test with Ubuntu 2020 LTS bzr 3.0.2
As pointed by @bcmills, upstream fixed this in 3.1.0 in https://github.com/breezy-team/breezy/commit/
30143860ced0ad9f42cbf18a119f2800117decff
Fixes #62620.
Change-Id: I9fa179a5293aec59496ddd401edec02e1080f1a5
GitHub-Last-Rev:
6066b05054877b33b78afbb32a81457c19f11c9b
GitHub-Pull-Request: golang/go#62652
Reviewed-on: https://go-review.googlesource.com/c/go/+/528437
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>