Test combining node flags with ts-node entrypoint and flags in process.execArgv #1657

Pretty sure we have a bug in our execArgv logic. It works only if there are not any other node flags in the execArgv array.

Impact for users:

This affects child_process.fork(), since it uses execArgv to create a similar child runtime.
For example, child_process.fork() fails if node is launched node --no-warnings ./node_modules/ts-node/dist/bin ./index.ts
With the fix, child_process.fork() will automatically preserve node flags and ts-node hooks

To test, create a script that spawns a child that spawns a grandchild. In the grandchild, inspect process.execArgv and process.argv

Run it like this:

node --no-warnings ./dist/bin.js --cwd-mode ./spawner.js

--no-warnings can be any node flag that is not understood by ts-node. --cwd-mode can be any ts-node flag that is not understood by node.

The bug is that we're prepending our modifications to the execArgv array; we should be appending them instead.