source/common/stats coverage is flaky

[RyanTheOptimist]

Post-submit source/common/stats coverage is flaky:
PASS: https://storage.googleapis.com/envoy-postsubmit/c8f3466/coverage/source/common/stats/index.html
FAIL: https://storage.googleapis.com/envoy-postsubmit/0811e14/coverage/source/common/stats/index.html

The difference appears to be lack of coverage of line 290 in coverage/source/common/stats/tag_extractor_impl.cc, an early return in TagExtractorTokensImpl::searchTags().

PASS: https://storage.googleapis.com/envoy-postsubmit/c8f3466/coverage/source/common/stats/tag_extractor_impl.cc.gcov.html
FAIL: https://storage.googleapis.com/envoy-postsubmit/0811e14/coverage/source/common/stats/tag_extractor_impl.cc.gcov.html

[RyanTheOptimist]

@jmarantz is this something we could write a simple unit test for to avoid the flake?

[RyanTheOptimist]

Just flaked on a PR too: https://dev.azure.com/cncf/envoy/_build/results?buildId=167357&view=logs&jobId=4930ecaf-18f4-5b3c-dea3-309729c3b3ae&j=4930ecaf-18f4-5b3c-dea3-309729c3b3ae&t=573d8780-d7b9-52e3-b4e0-a89886b0b9ff

[jmarantz]

did this start with #33191 ?

@alyssawilk

[phlax]

i think this was fixed here #33411