You can't use onInit with pipe extension

[jcubic]

Issue summary

If you use onInit with pipe file included pipe is never initialized because pipe onInit is overwritten by options.

Expected behavior

I expect onInit to work the same with or without pipe extension

Actual behavior

Pipe don't work if there is onInit.

Steps to reproduce

1. You can use Cowsay demo.
2. Add onInit with echo that is after the function.
3. Type fortune | say.

[jcubic]

The onInit is executed but you can't use term variable only use this. One caveat is that you can't use exec to use Pipe interpreter.

[jcubic]

reopening to document usage of term + exec with pipe.

[jcubic]

I was able to fix the issue, by invoking patched onInit when new pipe interpreter finished initializing, it require breacking change low level set_interpreter now return a promise.