elpy fails to find python on fresh installs of Ubuntu 20.04

[eanopolsky]

Summary

On a fresh install of Ubuntu Server 20.04, python is not symlinked to python3, so elpy does not work out of the box.

Systems that have been upgraded from previous Ubuntu releases to 20.04 do not seem to have this problem.

Steps to reproduce

1. Install Ubuntu Server 20.04 using only the default options.
2. Install emacs from the package manager.
3. Install elpy from melpa using the instructions at https://github.com/jorgenschaefer/elpy/blob/master/README.rst
4. Start emacs.
5. Run M-x elpy-config RET.

What I expected to happen:
I expected elpy to set up an RPC virtual environment and eventually display the config interface.

What actually happened:
Elpy displayed Cannot find executable 'python', please set 'elpy-rpc-python-command' to an existing executable. and did not display the config interface.

My configuration

OS

Ubuntu Server 20.04.3.

Result of (elpy-config)

Cannot find executable 'python', please set 'elpy-rpc-python-command' to an existing executable.

Elpy configuration in my init.el

(use-package elpy
  :ensure t
  :init
  (elpy-enable))

Workaround

Installing the python-is-python3 package works around this issue.