can't install jruby on Ubuntu 16.04: no openjdk-7-jre-headless package

[codeforkjeff]

I ran:

rvm get head
rvm install jruby

And got this output:

Searching for binary rubies, this might take some time.
Found remote file https://s3.amazonaws.com/jruby.org/downloads/9.1.2.0/jruby-bin-9.1.2.0.tar.gz
Checking requirements for ubuntu.
Installing requirements for ubuntu.
Updating systemjeffchiu password required for 'apt-get --quiet --yes update': ..-
..
Installing required packages: openjdk-7-jre-headless....
Error running 'requirements_debian_libs_install openjdk-7-jre-headless',
showing last 15 lines of /home/jeffchiu/.rvm/log/1468589813_jruby-9.1.2.0/package_install_openjdk-7-jre-headless.log
++ [[ -n '' ]]
++ command_to_run=(__rvm_sudo -p "%p password required for '$*': " "${command_to_run[@]}")
++ __rvm_sudo -p '%p password required for '\''apt-get --no-install-recommends --yes install openjdk-7-jre-headless'\'': ' apt-get --no-install-recommends --yes install openjdk-7-jre-headless
++ command sudo -p '%p password required for '\''apt-get --no-install-recommends --yes install openjdk-7-jre-headless'\'': ' apt-get --no-install-recommends --yes install openjdk-7-jre-headless
++ sudo -p '%p password required for '\''apt-get --no-install-recommends --yes install openjdk-7-jre-headless'\'': ' apt-get --no-install-recommends --yes install openjdk-7-jre-headless
Reading package lists...
Building dependency tree...
Reading state information...
Package openjdk-7-jre-headless is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'openjdk-7-jre-headless' has no installation candidate
++ return 100
++ return 100

Ubuntu 16.04 ships with openjdk 8, so the package should be "openjdk-8-jre-headless". I edited .rvm/scripts/functions/requirements/ubuntu and changed requirements_debian_define_java() to read:

requirements_debian_define_java()
{
  update-alternatives --list ${1:-java} >/dev/null 2>&1 ||
    requirements_check_fallback \
      openjdk-8-jre-headless openjdk-8-jdk oracle-j2sdk1.8 \
      openjdk-7-jre-headless openjdk-7-jdk oracle-j2sdk1.7 \
      openjdk-6-jre-headless opendjk-6-jdk oracle-j2sdk1.6
}

which worked. I'm not sure if there are other modifications that should accompany this change.