[bug]: Post-install script should stop suggesting custom origin setup once it's complete

[zetlen]

Describe the bug
When checking out and installing dependencies, a post-install script runs which logs:

$ node scripts/monorepo-introduction.js
Preparing packages...
Set up a custom origin for your copy of venia-concept:
	yarn buildpack create-custom-origin packages/venia-concept

It continues to log that custom origin notice even after you have run the command. It should detect that you've already run the command and stop logging.

To Reproduce
Steps to reproduce the behavior:

1. From repository root, run yarn run watch:venia.
2. If necessary, go through the steps and set up a custom origin. Then run yarn run watch:venia again, to observe the dev server starting and binding to the custom domain.
3. Quit the dev server.
4. Run yarn install.

Expected behavior
After install, the system should recognize that your repo is already set up. It should do no logging beyond "Preparing packages".

Screenshots
If applicable, add screenshots to help explain your problem.

Additional context
This is a recent addition to scripts/monorepo-introduction.js that exposes a small bug in Buildpack's configureHost function. It's a good first issue for community developers who want to work on tooling.

Possible solutions

• Modify configureHost.js so it always builds its hash from the absolute directory path.
• Modify monorepo-introduction.js so it always passes an absolute directory path to configureHost().
  The first is probably better.

Please let us know what packages this bug is in regards to:

• venia-concept
• venia-ui
• pwa-buildpack
• peregrine
• pwa-devdocs
• upward-js
• upward-spec

[LukasKiederle]

I am currently working on it