CBL 2.0 where expression clarification

From GitHub: https://github.com/couchbase/couchbase-lite-core/issues/392

Interpreting strings as booleans is weird. Most strings are false, but strings with nonzero numeric prefixes – in this case "2willowroad@nationaltrust.org.uk" -- are true.

Evaluating Expression.property("email").and(...) involves interpreting a string as a boolean. SQLite has no boolean type, just numbers, so it tries to parse the string as a number. Its number parser just stops when it reaches an illegal numeric character, returning whatever came before it, or zero if there were no digits. So "2willow" evaluates to 2, which is true.

This is counter-intuitive to be sure. But to change the way this works would require writing our own C function to do the conversion, and making our SQL query generator wrap it around every single expression that gets interpreted as a boolean. This would probably slow down queries; I don't know by how much.