I'll try. But it's not easy to reproduce. 
Sometimes `Monologue::Tag.where("lower(name) = ?", 'my_tag'.mb_chars.downcase.to_s).first` will result in such SQL:
 `SELECT 'monologue_tags'.* FROM 'monologue_tags' WHERE (lower(name) = 'm\0\0\0\0\0') ORDER BY 'monologue_tags'.'id' ASC LIMIT 1`.
I managed to reproduced it only once in command line.