ember-cli: Unable to run `ember init` in v2.6.0-beta.2

Running ember init gives me Cannot read property 'discoverChildAddons' of undefined .

ember-cli: 2.6.0-beta.2 node: 6.0.0 os: darwin x64 npm: 3.8.8

Output from ember version --verbose:

Cannot read property 'discoverChildAddons' of undefined
TypeError: Cannot read property 'discoverChildAddons' of undefined
    at CoreObject.extend.discoverAddons (/Users/steve/work/noovis-ui/node_modules/ember-cli/lib/models/addon.js:205:41)
    at CoreObject.extend.initializeAddons (/Users/steve/work/noovis-ui/node_modules/ember-cli/lib/models/addon.js:218:10)
    at /Users/steve/work/noovis-ui/node_modules/ember-cli/lib/models/addons-factory.js:48:17
    at visit (/Users/steve/work/noovis-ui/node_modules/ember-cli/lib/utilities/DAG.js:23:3)
    at visit (/Users/steve/work/noovis-ui/node_modules/ember-cli/lib/utilities/DAG.js:21:5)
    at DAG.topsort (/Users/steve/work/noovis-ui/node_modules/ember-cli/lib/utilities/DAG.js:82:7)
    at CoreObject.extend.initializeAddons (/Users/steve/work/noovis-ui/node_modules/ember-cli/lib/models/addons-factory.js:42:11)
    at Project.initializeAddons (/Users/steve/work/noovis-ui/node_modules/ember-cli/lib/models/project.js:379:36)
    at Project.eachAddonCommand (/Users/steve/work/noovis-ui/node_modules/ember-cli/lib/models/project.js:430:10)
    at module.exports (/Users/steve/work/noovis-ui/node_modules/ember-cli/lib/cli/lookup-command.js:33:13)