regression: pacstrap modifies host's /run

This seems to be a new regression in 29-1. Downgrading back to 28-2 restores normality.

$ ls -ld /run/systemd/netif
drwxr-xr-x 4 systemd-network systemd-network 120 Nov  7 09:03 /run/systemd/netif

$ sudo mkdir -pv /tmp/foo
mkdir: created directory '/tmp/foo'

$ sudo pacstrap /tmp/foo
<snip pacstrap output>

$ ls -ld /run/systemd/netif
drwxr-xr-x 4 systemd-timesync systemd-timesync 120 Nov  7 09:03 /run/systemd/netif

The ownership of /run/systemd/netif has changed from systemd-network to systemd-timesync thus screwing up network functionality on the host. Obviously, for this to happen the user/group id's must be different between the new root and the host:

$ grep 979 /tmp/foo/etc/passwd
systemd-network:x:979:979:systemd Network Management:/:/usr/bin/nologin

$ grep 979 /etc/passwd
systemd-timesync:x:979:979:systemd Time Synchronization:/:/usr/bin/nologin

The culprit is (unsurprisingly) 0feec4a5. In fact, this exact situation was mentioned in this comment. Any thoughts? cc @yhndnzj

Hmm, indeed... I guess for pacstrap we can stick to a fresh /run/ at least. But we need to come up with something else for arch-chroot.