cv: fix accidental transient tagging of potentially non-transient error.
cv: fix accidental transient tagging of potentially non-transient error.

R=yiwzhang

Change-Id: I3068407e0bebd65b5982e1e81c994afee1264165
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/2650156
Commit-Queue: Andrii Shyshkalov <a30c74fa30536fe7ea81ed6dec202e35e149e1fd@google.com>
Auto-Submit: Andrii Shyshkalov <a30c74fa30536fe7ea81ed6dec202e35e149e1fd@google.com>
Reviewed-by: Yiwei Zhang <50b2a565e2e78c292794832469a30ce5abc9959c@google.com>

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