systemd package specifies MIT-0 license, which contains a custom copyright line, but does not copy it into /usr/share/licenses/systemd

Description:

systemd lists the MIT-0 license as well as various others; it's used for its docs and config files: https://github.com/systemd/systemd/blob/main/LICENSES/README.md

The MIT-0 license text is here: https://github.com/systemd/systemd/blob/main/LICENSES/MIT-0.txt

This is a custom-ish license like BSD-3-Clause; it has an SPDX identifier, but contains a custom copyright line, so it can't be included in /usr/share/licenses/common by the licenses package.

How to fix:

Adding this line to the PKGBUILD's package_systemd() function will probably fix the issue:

install -D -m0644 "$srcdir"/systemd/LICENSES/MIT-0.txt -t "$pkgdir"/usr/share/licenses/$pkgname/

Additional info:

• This affects systemd since 255.3 and this commit, which added the MIT-0 license to the package license list: 92c153cb

Steps to reproduce:

1. pacman -Syu systemd
2. pacman -Qi systemd
3. Observe that MIT-0 is listed among the licenses.
4. ls -al /usr/share/licenses/systemd
5. Observe that the directory doesn't exist.