Auto merge of #21193 - servo:jdm-patch-17, r=asajeffrey

Recreate virtualenv from scratch when syncing WPT

This fixes #21180 and attempts to work around #21145.

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etc/ci/buildbot_steps.yml

@@ -147,6 +147,7 @@ linux-nightly:
   - ./mach test-perf
   - python3 ./etc/ci/performance/download_buildbot_timings.py --verbose
   - aws s3 sync --size-only --acl public-read ./etc/ci/performance/output s3://servo-perf
+  - rm -rf ./python/_virtualenv
   - ./etc/ci/update-wpt-checkout fetch-and-update-expectations
   - ./etc/ci/update-wpt-checkout open-pr
   - ./etc/ci/update-wpt-checkout cleanup

etc/ci/performance/test_perf.sh

@@ -39,8 +39,8 @@ fi
 # Make sure we're running with an up-to-date warc test repo
 git -C ${WARC_DIR} pull --progress
 
-virtualenv venv ./perf-venv --python="$(which python3)"
-PS1="" source ./perf-venv/bin/activate
+virtualenv venv --python="$(which python3)"
+PS1="" source venv/bin/activate
 # `PS1` must be defined before activating virtualenv
 pip install \
     "boto3>=1.4.0" \