Recovery partition silently nuked existing install instead of installing onto usb stick as selected

[kylebakerio]

Distribution (run cat /etc/os-release):
20.10

Related Application and/or Package Version (run apt policy $PACKAGE NAME):
installer flow (directed here from one of the engineers on reddit)

Issue/Bug Description:
I have installed from one usb set up for live boot to another usb that I'm making a 'portable/persistent' install on before. On this day, though, I decided to instead just install from the recovery partition onto a usb instead of creating a live-install usb.

While the recovery boot's installer seemed to allow me to select clean installing onto the usb stick, it silently nuked my actual install instead. (The usb stick continues to have the broken install that was on it before this procedure.)

Further description:

https://www.reddit.com/r/pop_os/comments/mkpjfd/critical_bug_wiped_my_entire_install/

Full install broken up into three small videos to fit with github size limits:

WhatsApp.Video.2021-04-07.at.14.16.12.mp4

WhatsApp.Video.2021-04-07.at.14.38.05.mp4

WhatsApp.Video.2021-04-07.at.14.38.31.mp4

Screenshot of the terminal in the install:

Steps to reproduce (if you know):

1. Install pop 20.10 to your hard drive (mine is nvme)
2. plug in a usb stick (mine had an existing install of pop 20.10 that I intended to overwrite)
3. boot from the hard drive's recovery partition
4. attempt to install to the usb stick (clean install, select usb stick, do not encrypt)
5. instead, you'll find your hard drive's install has been cleanly overwritten

Expected behavior:

• since the recovery partition is 'just a live install', it should be able to manage an install to any drive, not just the drive it is installed on.
• if it can't, it shouldn't list the ability to do this
• it should certainly never install than a different drive than the user selected

Other Notes:
This happened on accident the first time. Since I had a freshly wiped system, I speculated this might be the cause, and went through it a second time filming it just for the bug report. (I did go through the welcome screen and install a file on the desktop just so I could verify that the install was indeed wiped a second time.) I probably should have tried to use some recovery software, but I was just in a bit of shock.

It happened exactly as I understood it to happen the first time.

Note that it did not wipe my windows partition that was on the same drive, as would be expected from a real 'clean install' with just a whole drive selected (right?).

[bflanagin]

Thanks for the detailed report @kylebakerio , I'm able to replicate the issue consistently on my end.