Fixed PACKAGE_NAMES export in travis.yml.

Author: Michael Koval

.travis.yml

@@ -20,9 +20,9 @@ before_install:
 - curl -sSo distribution.yml "${DISTRIBUTION}"
 - git clone https://github.com/personalrobotics/pr-cleanroom.git scripts
 - ./scripts/internal-setup.sh
+- export PACKAGE_NAMES="$(./scripts/internal-get-packages.py distribution.yml ${REPOSITORY})"
 install:
 - mv "${TRAVIS_BUILD_DIR}" src
-- export PACKAGE_NAMES="$(./scripts/internal-get-packages.py distribution.yml '${REPOSITORY}')"
 - ./scripts/internal-distro.py --workspace=src distribution.yml --repository "${REPOSITORY}"
 script:
 - ./scripts/internal-build.sh ${PACKAGE_NAMES}