Comment 11 for bug 1524526

Since it was only 98% clear :-), here a summary of a short and easy guide to trigger the issue in e.g. a container:

#1 install dovecot+lucene
sudo apt-get install dovecot-lucene
#2 configure lucene
sed -ie 's/#mail_plugins = $/mail_plugins = $mail_plugins fts fts_lucene/' /etc/dovecot/conf.d/10-mail.conf
sed -ie 's/^plugin {$/plugin {\n fts = lucene\n fts_lucene = whitespace_chars=@./' /etc/dovecot/conf.d/90-plugin.conf
#3 do soething with dovecot
service dovecot reload
doveadm pw -s SSHA256 -p verysecretindeed

Fatal: Couldn't load required plugin /usr/lib/dovecot/modules/lib21_fts_lucene_plugin.so: dlopen() failed: /usr/lib/dovecot/modules/lib21_fts_lucene_plugin.so: undefined symbol: _ZN6lucene8analysis8snowball16SnowballAnalyzerC1EPFiPKvmP6bufferEPKc

Note that while it won't save us from this being a bug, the comment at http://wiki2.dovecot.org/Plugins/FTS/Lucene is worth to note as a lucene user:
Quote: "NOTE: Although the fts-lucene plugin works, it's using CLucene library, which is very old and has some bugs. It's a much better idea to use fts-solr instead, which has much more features and is more stable."