sql: more helpful error in logic test output
sql: more helpful error in logic test output

If your `query error` line is identical to the output but fails to match
it as a regex, the LogicTest will inform you that you probably forgot to
escape your string.

paperstreet/cockroach,paperstreet/cockroach,paperstreet/cockroach,paperstreet/cockroach,paperstreet/cockroach,paperstreet/cockroach,paperstreet/cockroach,paperstreet/cockroach