ObjectionJS: Instance method $relatedQuery doesn't reuse knex instance

Minimal case to demonstrate the ObjectionJS issue: Vincit/objection.js#1616

Tested with: nodejs: v12.13.0 MariaDB: 10.1.16

Requirement

A working MySQL/MariaDB database

Install

• Import draft.sql into your database server
• Adjust connection string in index.js:3 according to your setup
• Execute npm install
• Execute nodejs index.js