Fix dictionary reference in release_builder.py (#872)
Fix dictionary reference in release_builder.py (#872)

* Fix dictionary reference in release_builder.py

* Remove redundant string cast

mesosphere/dcos-commons,mesosphere/dcos-commons,vishnu2kmohan/dcos-commons,mesosphere/dcos-commons,vishnu2kmohan/dcos-commons,vishnu2kmohan/dcos-commons,mesosphere/dcos-commons,vishnu2kmohan/dcos-commons,mesosphere/dcos-commons,vishnu2kmohan/dcos-commons