RFR: 1840: A test failed due to the combination of SKARA-1823 and SKARA-755

[Zhao Song]

This patch fixes MailingListBridgeBotTests::simpleArchive.

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Commit messages:
 - SKARA-1840

Changes: https://git.openjdk.org/skara/pull/1483/files
 Webrev: https://webrevs.openjdk.org/?repo=skara&pr=1483&range=00
  Issue: https://bugs.openjdk.org/browse/SKARA-1840
  Stats: 4 lines in 1 file changed: 1 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/skara/pull/1483.diff
  Fetch: git fetch https://git.openjdk.org/skara pull/1483/head:pull/1483

PR: https://git.openjdk.org/skara/pull/1483