Without this, secondary addresses would get deleted when the primary one is. This is not
the desired behavior when one would like to transition from one address to another in the
same subnet (such as when a new IP address is given over DHCP).
In networkd, when given a new IP over DHCP we will add it, without explicitly removing the
old one first (and hence never have a window without an IP address configured). Assuming the
addresses are in the same subnet, that means that the old address is the primary and the new
address is the secondary one. Once the old address expires, the kernel will drop it. With the
old behavior this means that both addresses would be lost, which is clearly not what we want.
With the new behavior, only the old address is lost, and the new one is promoted to primary.
Reported by Michael Olbrich <m.olbrich@pengutronix.de>
We finally got the OK from all contributors with non-trivial commits to
relicense systemd from GPL2+ to LGPL2.1+.
Some udev bits continue to be GPL2+ for now, but we are looking into
relicensing them too, to allow free copy/paste of all code within
systemd.
The bits that used to be MIT continue to be MIT.
The big benefit of the relicensing is that closed source code may now
link against libsystemd-login.so and friends.
