Ubuntu package "python3-virtualenv" accepted in step I-5, but causes step II-1 to fail

**1. Please specify the following:**
- OS: Ubuntu 18.04
- Shell: Bash

- [X ] **I have reviewed the troubleshooting tips described [here](/home/toruitas/.pyenv/versions/3.7.2/bin/virtualenv) and they do not solve my problem**

**2. Description**
Attempting to install using `./aws-elastic-beanstalk-cli-setup/scripts/bundled_installer`

Gives the following output:

```
==============================================
I. Installing Python
==============================================

*************************************************************
1. Determining whether pyenv is already installed and in PATH
*************************************************************
- pyenv found in PATH. Won't clone pyenv git repository from GitHub

*******************************************
2. Temporarily export necessary pyenv paths
*******************************************

****************************************************************************
3. Checking whether Python can be downloaded (through curl, wget, or aria2c)
****************************************************************************

************************************************************
4. Installing Python 3.7.2. This step may take a few minutes
************************************************************
- Python 3.7.2 is installed at /home/username/.pyenv/versions/3.7.2/bin

***************************************************************************
5. Installing virtualenv using /home/username/.pyenv/versions/3.7.2/bin/pip
***************************************************************************
Requirement already satisfied: virtualenv in /home/username/.local/lib/python3.7/site-packages (16.7.5)
WARNING: You are using pip version 19.2.3, however version 19.3.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

==============================================
II. Creating self-contained EBCLI installation
==============================================

******************************************
1. Creating exclusive virtualenv for EBCLI
******************************************
/bin/sh: 1: /home/username/.pyenv/versions/3.7.2/bin/virtualenv: not found
Exiting due to failure
```

It looks like the Ubuntu system installed python3-virtualenv is acceptable for part of the installation process, but this causes problems later.

Run ./aws-elastic-beanstalk-cli-setup/scripts/bundled_installer on Ubuntu 18.04 with Bash and inspect the transition from step I-5 to II-1. Trace why the accepted python3-virtualenv installation leaves /home/username/.pyenv/versions/3.7.2/bin/virtualenv unavailable; done means the self-contained EBCLI installation completes successfully.

Written by the indexing model from the issue text.