ITS#9121 fix dynlist_filter_dup for substring filter

3 jobs for master in 25 minutes and 7 seconds (queued for 2 seconds)
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passed build-gnutls-mit #2609

00:24:45

passed build-no-threads-no-slapd #2607

00:02:31

passed build-openssl-heimdal #2608

00:25:06