Parameters::read() with checked = true is broken

[fubuloubu]

Took me a while to figure this one out, and I'm not entirely sure what the issue may be, but I've definitely narrowed it down to the fact that this API (bellman::groth16::Parameters::read<R: Read>(reader: R, checked: bool) -> Result<Self>) locks up my machine when I specify checked = true.

It seems like it works just fine when I don't use it (checked = false), so I'm curious if the flag is even necessary or what it does where this behavior is encountered.