---
api: 2

# Basic Drush Make file for Drupal. Be sure to update the drupal_major_version
# variable inside config.yml if you change the major version in this file.

# Drupal core (major version, e.g. 6.x, 7.x, 8.x).
core: 8.x

projects:

  drupal:
    type: core
    version: 8.0.x

  devel: 1.x-dev

---
api: 2

# Basic Drush Make file for Drupal. Be sure to update the drupal_major_version
# variable inside config.yml if you change the major version in this file.

# Drupal core (major version, e.g. 6.x, 7.x, 8.x).
core: "8.x"

projects:

  drupal:
    type: "core"
    version: "8.0.x"

  devel: "1.x-dev"

Use quotation marks for property values
Use quotation marks for property values

It seems like Drush is fine with some non-quoted property values, but has problems with others. Here is an example where I modified this default make file and ended up with problems:
https://gist.github.com/mchelen/0a2aa697ca208e94c684

For the sake of consistency, maybe it is best to use quotation marks for all values?