http buffer filter integration test flake

[zuercher]

This seems to happen only in coverage tests. The last test logged as starting is always:

[----------] 1 test from Protocols/BufferIntegrationTest
[ RUN      ] Protocols/BufferIntegrationTest.RouterRequestPopulateContentLengthOnTrailers/IPv4_Http2Downstream_HttpUpstream
external/bazel_tools/tools/test/collect_coverage.sh: line 128: 27497 Segmentation fault      (core dumped) "$@"
+ TEST_STATUS=139
+ touch /build/tmp/_bazel_bazel/b570b5ccd0454dc9af9f65ab1833764d/sandbox/processwrapper-sandbox/4581/execroot/*****/bazel-out/k8-fastbuild/testlogs/test/coverage/coverage_tests/shard_24_of_50/coverage.dat
+ [[ 139 -ne 0 ]]
+ echo --
--
+ echo Coverage runner: Not collecting coverage for failed test.
Coverage runner: Not collecting coverage for failed test.
+ echo The following commands failed with status 139
The following commands failed with status 139
+ echo /build/tmp/_bazel_bazel/b570b5ccd0454dc9af9f65ab1833764d/sandbox/processwrapper-sandbox/4581/execroot/*****/bazel-out/k8-fastbuild/bin/test/coverage/coverage_tests.runfiles/*****/test/coverage/coverage_tests --gmock_default_mock_behavior=2 '--log-path /dev/null' '-l trace'
/build/tmp/_bazel_bazel/b570b5ccd0454dc9af9f65ab1833764d/sandbox/processwrapper-sandbox/4581/execroot/*****/bazel-out/k8-fastbuild/bin/test/coverage/coverage_tests.runfiles/*****/test/coverage/coverage_tests --gmock_default_mock_behavior=2 --log-path /dev/null -l trace
+ exit 139

Master commits where this failure occurred:
4e1753f
7e60f33
527853b
f75d47e
9105aea
bbdc33e
7801d05

[mattklein123]

Haven't seen this in a while, closing for now.