Use apg-get install with --no-upgrade.
@@ -12,7 +12,7 @@ pushd "$DEPS_DIR"
# Install dependencies from package manager.
if [ "$TRAVIS_OS_NAME" == "linux" ]; then
sudo apt-get -qq update
- sudo apt-get install --no-install-recommends \
+ sudo apt-get install --no-install-recommends --no-upgrade \
doxygen \
graphviz \
python-dev \
