Bools coerced to 0/1 in query results

[jtcohen6]

This is probably the result of allowing newer versions of agate (#3585):

I thought we had a fix in v0.21 (#3499) that prevented agate from coercing query results (including from booleans to 0/1, wireservice/agate#733), but it clearly still is, somehow.

Let's confirm whether the agate dependency is the cause, and if so:

• (worse fix) Roll it back to 1.6.1
• (better fix) Fix the type coercion logic