Bower error when pushing to Heroku : bower ENOTDIR ENOTDIR, not a directory '/tmp/build_xxx/bower_components

I’ve got problem when I try to push a ember-cli project on Heroku.
This is the log which is return to me.

Total 0 (delta 0), reused 0 (delta 0)
remote: Compressing source files... done.
remote: Building source:
remote: -----> Fetching custom git buildpack... done
remote: -----> Ember CLI app detected
remote: -----> Exporting config vars to environment
remote: -----> Building environment: production
remote: -----> Requested node range:  0.12.7
remote: -----> Resolved node version: 0.12.7
remote: -----> Downloading and installing node
remote: -----> Using default npm version: 2.11.3
remote: -----> Downloading and installing nginx
remote: -----> Adding boot script
remote: -----> Copying configs
remote: -----> Creating node_modules cache directory
remote: -----> Creating bower_components cache directory
remote: -----> Installing bower which is required by other  dependencies
remote:        bower@1.6.2 node_modules/bower
remote: -----> Pruning cached dependencies not specified in package.json
remote: -----> Pruning cached bower dependencies not specified in   bower.json
remote:        bower ENOTDIR       ENOTDIR, not a directory '/tmp/build_7092e0e145a6f8787208ecf8b53c932a/bower_components'
remote:  !     Push rejected, failed to compile Ember CLI app
remote: Verifying deploy....
remote: !   Push rejected to my-app 

I’ve tried to purge the cache with the heroku-repo but still the same problem.

If I compile the project with ember build, there’s no problem. Just the message:

bower invalid-meta  ember is missing "ignore" entry in bower.json

The deployment worked before.

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