ASTERIXDB-1127: fix ExtractCommonOperatorsRule. Change-Id: I16933a4b72432b5fbd523ca80ce6426f6b6743a9 Reviewed-on: https://asterix-gerrit.ics.uci.edu/691 Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu> Reviewed-by: Pouria Pirzadeh <pouria.pirzadeh@gmail.com> Reviewed-by: Till Westmann <tillw@apache.org>