Docker-issue with ONBUILD-commands

On up to date docker installation the ONBUILD commands in the
old docker image we use doesn't seem to run as they should,
so I've copied the commands into the Dockerfile. If ONBUILD-
commands run it doesn't change anything so there is no
significant downside.

Dockerfile

@@ -2,3 +2,9 @@ FROM ruby:1.9-onbuild
 
 EXPOSE 3000
 CMD /usr/local/bin/ruby web_server.rb
+
+# -onbuild should have taken care of this
+COPY Gemfile /usr/src/app/
+COPY Gemfile.lock /usr/src/app/
+RUN bundle install
+COPY . /usr/src/app