The xenial image is using version 1.29.7 of rvm (as of today) while version 1.29.9 is the latest stable version available.
As a result, using jruby-9 alias will install jruby version 9.2.5.0 instead of 9.2.7.0.
Please consider using the latest stable version of rvm.
Please note that it’s not possible to manually update rvm in a before_install task because the rvm matrix runs before.
You can’t do rvm get stable before the rvm command is run (the before_install hook happens after that).
Using dist: bionic fails for Ruby 2.0 and 2.1 (which unfortunately we still need to support) with: Requested binary installation but no rubies are available to download, consider skipping