after user revoked channel access, doc updated on CBL not purged after push-pull replication

CBL 3.0.0-108 / SG Version: 3.0.0-392

• Steps to Reproduce:
  1. on SGW create a user autotest with channel A and channel B
  2. on SGW create 10 docs with channel A, and 15 docs with channel B, and 9 docs with channel A and B
  3. on CBL start a one-shot pull replicator with the user credential
  4. assertion: doc count on CBL equals to docs on SGW, both are 34 (10 + 15 + 9)
  5. on SGW remove the user from channel A
  6. on cbl randomly pick 2 channel A-only docs update 3 times (in this case, doc CH_A_doc_0 and CH_A_doc_7 are picked) and 3 docs belong to A and B, update 2 times 
  7. on CBL, start replication with push-pull replicator type
  8. assertion all channel A-only docs get purged on CBL

• Actual Result:

CH_A_doc_7 is not purged at step 8

• Expected Result:

both CH_A_doc_0 and CH_A_doc_7 get purged at step 8

• Logs :
  CBL LOGS:  (attached)

• Github link for the code:

https://github.com/couchbaselabs/mobile-testkit/blob/feature/channel-revocation-cbl-1/testsuites/CBLTester/CBL_Functional_tests/TestSetup_FunctionalTests/test_channel_revocation.py#L718

• Jenkins job failure link:

http://uberjenkins.sc.couchbase.com:8080/view/Channel%20Revocation/job/DOTNET-Net-windows-XATTRS-DELTA-SYNC-Functional-Channel-Revocation-tests/7/testReport/testsuites.CBLTester.CBL_Functional_tests.TestSetup_FunctionalTests/test_channel_revocation/test_user_removed_from_channel_with_doc_mutation_pushAndPull_/

• Pytest Command
  pytest -s --timeout 3600 --liteserv-version=3.0.0-108 --liteserv-host=10.100.161.140 --liteserv-port=8080 --xattrs --delta-sync --sg-ssl --enable-file-logging --no-conflicts --disable-persistent-config --disable-admin-auth --enable-server-tls-skip-verify --server-ssl --sync-gateway-version=3.0.0-392 --mode=cc --server-version=7.0.0-5302 --liteserv-platform=net-msft --create-db-per-test=cbl-test testsuites/CBLTester/CBL_Functional_tests/TestSetup_FunctionalTests/test_channel_revocation.py -k test_user_removed_from_channel_with_doc_mutation[pushAndPull] 

• What is the last build this test passed: