I've cloned civicrm-core (4.7.28) and civicrm-drupal (switched to branch 8.x-4.7.28-rc) into my top level modules dir of my Drupal 8.4. I was able to install dependencies into vendor dir for civicrm-core using composer. I get the following errors when trying to do same for civicrm-drupal:
Loading composer repositories with package information Updating dependencies (including require-dev) Your requirements could not be resolved to an installable set of packages.
Problem 1 - The requested package civicrm/civicrm-core could not be found in any version, there may be a typo in the package name.
Potential causes: - A typo in the package name - The package is not available in a stable-enough version according to your minimum-stability setting see https://getcomposer.org/doc/04-schema.md#minimum-stability for more details. - It's a private package and you forgot to add a custom repository to find it
From what I gather the problem is simply a path issue, as civicrm-core 4.7.28 is in a peer dir. As it seems bad practice to modify the composer.json file to point to local path and I wish to keep core/drupal projects in separate dir, there must be a simple solution which I've been unable to stumble on thus far.