Pin bundler where needed

tools/dockerfile/distribtest/ruby_centos6_x64/Dockerfile

@@ -30,7 +30,7 @@ RUN /bin/bash -l -c "rvm use --default ruby-2.3.8"
 RUN /bin/bash -l -c "echo 'gem: --no-document' > ~/.gemrc"
 RUN /bin/bash -l -c "echo 'export PATH=/usr/local/rvm/bin:$PATH' >> ~/.bashrc"
 RUN /bin/bash -l -c "echo 'rvm --default use ruby-2.3.8' >> ~/.bashrc"
-RUN /bin/bash -l -c "gem install bundler --no-document"
+RUN /bin/bash -l -c "gem install bundler -v 1.17.3 --no-document"
 
 RUN mkdir /var/local/jenkins
 

tools/dockerfile/distribtest/ruby_centos7_x64/Dockerfile

@@ -26,7 +26,7 @@ RUN /bin/bash -l -c "rvm use --default ruby-2.3.8"
 RUN /bin/bash -l -c "echo 'gem: --no-document' > ~/.gemrc"
 RUN /bin/bash -l -c "echo 'export PATH=/usr/local/rvm/bin:$PATH' >> ~/.bashrc"
 RUN /bin/bash -l -c "echo 'rvm --default use ruby-2.3.8' >> ~/.bashrc"
-RUN /bin/bash -l -c "gem install bundler --no-document"
+RUN /bin/bash -l -c "gem install bundler -v 1.17.3 --no-document"
 
 RUN mkdir /var/local/jenkins
 

tools/dockerfile/distribtest/ruby_fedora20_x64/Dockerfile

@@ -29,7 +29,7 @@ RUN /bin/bash -l -c "rvm use --default ruby-2.3.8"
 RUN /bin/bash -l -c "echo 'gem: --no-document' > ~/.gemrc"
 RUN /bin/bash -l -c "echo 'export PATH=/usr/local/rvm/bin:$PATH' >> ~/.bashrc"
 RUN /bin/bash -l -c "echo 'rvm --default use ruby-2.3.8' >> ~/.bashrc"
-RUN /bin/bash -l -c "gem install bundler --no-document"
+RUN /bin/bash -l -c "gem install bundler -v 1.17.3 --no-document"
 
 RUN mkdir /var/local/jenkins
 

tools/dockerfile/distribtest/ruby_fedora21_x64/Dockerfile

@@ -32,7 +32,7 @@ RUN /bin/bash -l -c "rvm use --default ruby-2.3.8"
 RUN /bin/bash -l -c "echo 'gem: --no-document' > ~/.gemrc"
 RUN /bin/bash -l -c "echo 'export PATH=/usr/local/rvm/bin:$PATH' >> ~/.bashrc"
 RUN /bin/bash -l -c "echo 'rvm --default use ruby-2.3.8' >> ~/.bashrc"
-RUN /bin/bash -l -c "gem install bundler --no-document"
+RUN /bin/bash -l -c "gem install bundler -v 1.17.3 --no-document"
 
 RUN mkdir /var/local/jenkins