[Core] Unable to boot Sugar to BOOT_SUGAR_FULL level

The Quotes module uses `$beanFiles` on `require_once` on the top of the class
file.

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |