[Error] Fedora distrobox can't access /dev/null ?

**Describe the bug**
Rootful Fedora 43 Distrobox, `fedpkg mockbuild` is failing, I suspect due to `/dev/null` being inaccessible?

**To Reproduce**
1) Create Rootful F43 Distrobox, via `distrobox create --root -i quay.io/fedora/fedora:43 -n fpkg --init -additional-packages 'systemd fedora-packager'`
2) Grab fedora sources via `fedpkg co niri-settings` (just using niri-settings as an example, this is happening with all attempted mockbuilds, regardless of package)
3) Run `fedpkg mockbuild` on sources
4) mockbuild process fails, during setup of the mock buildroot, suspected due to:
```
>>> Running %triggerin scriptlet: info-0:7.2-7.fc44.x86_64
>>> Non-critical error in %triggerin scriptlet: info-0:7.2-7.fc44.x86_64
>>> Scriptlet output:
>>> /var/tmp/rpm-tmp.J2jliB: line 2: /dev/null: Permission denied
>>>
>>> [RPM] %transfiletriggerin(info-7.2-7.fc44.x86_64) scriptlet failed, exit status 1
>>> Running %triggerpostun scriptlet: info-0:7.2-7.fc44.x86_64
>>> Non-critical error in %triggerpostun scriptlet: info-0:7.2-7.fc44.x86_64
>>> [RPM] %transfiletriggerpostun(info-7.2-7.fc44.x86_64) scriptlet failed, exit status 1
```

**Expected behavior**
`fedpkg mockbuild` runs and sets up the buildroot properly and creates a local rpm

**Logs**
Run the commands with `--verbose` and post the log here as a file upload

[distrobox-fpkg-verbose.txt](https://github.com/user-attachments/files/24719644/distrobox-fpkg-verbose.txt)

[podman-logs.txt](https://github.com/user-attachments/files/24719664/podman-logs.txt)

**Desktop (please complete the following information):**

- Podman 5.7.1
- distrobox version: 1.8.2.2
- Kalpa Desktop (openSUSE Tumbleweed/MicroOS)
- Distribution provided RPM packages

**Additional context**

[mockbuild.txt](https://github.com/user-attachments/files/24720032/mockbuild.txt) Log of the actual mockbuild

Apparently, in Fedora 42, rpmbuild was allowed to ignore these "Non-Critical Errors" in mockbuild, and proceed normally. In F43 and Rawhide, that policy has now changed.

I don't *actually* know what the issue is. Or if access to `/dev/null` has anything to do with it, but those errors were there with F42, and I could build fine. This may, or may not be a distrobox issue with permissions, but so far, I can't seem to narrow down where the actual problem is.