In the UK, 'small beer' is also an idiom meaning 'unimportant' or 'uninteresting'.
The first usage of this metaphorical sense appeared in print in Othello (1603), by William Shakespeare.
IAGO: She was a wight, if ever such wight were,--
DESDEMONA: To do what?
IAGO: To suckle fools and chronicle small beer.
While this usage is not too uncommon in the UK and France (petite bière), in America it is fairly rare, and you are much more likely to hear 'small potatoes' used instead.