message: Update rust version for redhat.
diff: @@ -36,7 +36,7 @@ RUN wget https://repos.fedorapeople.org/repos/dchen/apache-maven/epel-apache-mav
  RUN sed -i s/\$releasever/6/g /etc/yum.repos.d/epel-apache-maven.repo
  RUN yum install -y apache-maven
  -ENV RUST_ARCHIVE=rust-1.20.0-x86_64-unknown-linux-gnu.tar.gz
  +ENV RUST_ARCHIVE=rust-1.21.0-x86_64-unknown-linux-gnu.tar.gz
  ENV RUST_DOWNLOAD_URL=https://static.rust-lang.org/dist/$RUST_ARCHIVE
  RUN mkdir -p /rust
  