Comment 4 for bug 2059907

To be clear, as I understand it, this is the situation caused by running the installer twice in one session. The problem is caused because the drive is still mounted at /tmp. This occurs regardless of whether or not Calamares is interrupted in the middle of installation or if it is allowed to complete the installation and is exited cleanly.

I note that we use the umount module in our penultimate step of the installation (the last being the finished module). calamares-settings-lubuntu doesn't include a config file for it. I would presume it would then use the defaults. There is only one option which, by default, should cause the module to run if one of the previous modules fails.

That said, I see two potential explanations for why the umount doesn't seem to be working:
 1. the missing config file = calamares-settings-ubuntu issue
 2. the module isn't working as expected = calamares issue

With those potential issues resolved, I think the next logical step would be to *also* include running the umount module *before* the partioning step. This will deal with the case where the user has done something else in the live session that mounts the drive.

Obviously, the umount module isn't expected to run if Calamares is forcibly closed. There's really nothing that can be done about that situation.

I think the likelihood of users running the installer twice is slim to none, so I'm calling this low.