chore: install ruby-bundler
Fixes recent build failures in the Travis CI environment.
This closes #1158
diff --git a/build/docker/debian/Dockerfile b/build/docker/debian/Dockerfile
index 99eda7a..7c15109 100644
--- a/build/docker/debian/Dockerfile
+++ b/build/docker/debian/Dockerfile
@@ -83,6 +83,8 @@
libio-socket-ssl-perl \
libnet-ssleay-perl
+RUN echo "deb http://ftp.debian.org/debian jessie-backports main" > /etc/apt/sources.list.d/jessie-backports.list
+RUN apt-get update && apt-get -t jessie-backports install -y ruby-bundler
RUN apt-get update && apt-get install -y --no-install-recommends \
`# Php dependencies` \
php5 \