Lpeg 0.12: "grammar has too many rules"

[Daurnimator <quae@...>]

I'm looking for an email parser for lua, and came across Sean Conner's work [1]
Trying to run it with Lpeg 0.12 you get a failure:
    bad argument #1 to '?' (grammar has too many rules)

It used to work with Lpeg 0.10 [2], what new limits has Lpeg 0.12 brought along?

[1] https://github.com/spc476/LPeg-Parsers/blob/master/email.lua
[2] https://github.com/spc476/LPeg-Parsers/issues/2#issuecomment-23723020