[Bug]: Various Flatpak test failures due to fusermount error

[TheComputerGuy96]

Checklist

• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a bug that matches the one I want to file, without success.
• If this is an issue with a particular app, I have tried filing it in the appropriate issue tracker for the app (e.g. under https://github.com/flathub/) and determined that it is an issue with Flatpak itself.
• This issue is not a report of a security vulnerability (see here if you need to report a security issue).

Flatpak version

1.12.7

What Linux distribution are you using?

Arch Linux

Linux distribution version

No response

What architecture are you using?

x86_64

How to reproduce

1. Have an up-to-date Arch Linux install ready using the Arch install guide
2. Install all the dependencies listed in the Flatpak PKGBUILD
3. Clone the Flatpak Arch package build files
4. Run makepkg -s in the directory with the build files

(these instructions are bad, but I want to quickly post this issue)

Expected Behavior

There should be no test failures

Actual Behavior

There are ~26 test failures because of this error:

+ fusermount -u /tmp/test-flatpak-iyk1Fm/runtime/doc
fusermount: entry for /tmp/test-flatpak-iyk1Fm/runtime/doc not found in /etc/mtab

Which causes the failing tests to say too few tests run

Additional Information

The error above shows up near all failing tests

I also tried building 1.13.3 but I get the same error (and I tried rebooting my system too)

BTW my build has a patch to remove ptrace from blocked syscalls (VMProtect needs ptrace for some reason), but i doubt that would affect the results

[swick]

Running into the same issue on a Fedora 38 toolbox.

[swick]

The output is misleading but the root cause is simply fuse3 not being installed. E.g. in the toolbox a sudo dnf install fuse3 fixed the issue. Seems like the arch PKGBUILD needs updating as well.

Still running into issues on toolbox but they are unrelated. This issue can be closed.