Look for the distro name in /etc/os-release and /usr/lib/os-release instead of relying on the external lsb-release tool, which may not be installed on the system (it is not in Arch by default). The lsb-release method is kept as a fallback.
- R134:2f4f9a48fcb8: Query os-release for distro name
Distro name is displayed correctly in the sources list in Arch Linux without lsb-release installed
According to https://www.freedesktop.org/software/systemd/man/os-release.html both NAME and PRETTY_NAME should be suitable for presentation to the user, the difference being that PRETTY_NAME may contain the distro version and codename. IMO NAME fits better here, but I don't mind changing it if you'd rather use PRETTY_NAME.