Transaction independence issue reproduction

Includes test showing that separate transactions appear to be rolled back when one of them fails.

Last working version: 0.3.18-dev.3cda7ec
Broken since version: 0.3.18-dev.0f11739

Installation & running

deno install --allow-scripts # required for sqlite3, used for running in-memory
deno test -A # flag gives all permissions

Switching version to last working

deno add npm:typeorm@0.3.18-dev.3cda7ec