This is what happened before this patch (edited for brevity):
dracut-cmdline-ask.service in modules.d/98dracut-systemd, which invokes
dracut-cmdline-ask.sh. This script and systemd-vconsole-setup are
started in parallel for the same console (tty1).
Then dracut-cmdline-ask quits immediately without doing anything (unless
rd.cmdline=ask is given). As this is a bash script and it gets tty as
stdin as specified in its *.service, this triggers the hangup of tty1 at
its exit.
Meanwhile systemd-vconsole-setup continues and tries some ioctls after
that, but they fail because of the hung up tty1.
The usual culprit for starting systemd-vconsole-setup early on is
plymouth-start.service, even if plymouth.enable=0 is set.
A popular (and annoying) symptom of this as reported by users was
the inability use their configured keyboard layout in plymouth when
unlocking their crypted block devices.
Reference: boo#1055834
When extra devices are added, initqueue should be enabled to make sure
those devices are present, so following services and routines could
use those devices.
See PR #442 for more detail.
Use multiple lower layer directories in a single OverlayFS mount with
a transient overlay directory.
Tolerate a command line with rd.live.overlay.readonly and NO persistent
overlay by reconfiguring the OverlayFS mount options.
Use more compatible shell syntax for testing symlinks, and use printf
instead of echo -e.
A simplified root filesystem structure may be provided for OverlayFS
overlays by squashing the root filesystem directly instead of squashing
an embedded image file at /LiveOS/rootfs.img. Detect and configure
such a squashed root filesystem for live booting.
For OverlayFS boots, avoid the read-only Device-mapper linear device
at /dev/mapper/live-base.
Create a consistent device link at /dev/live-base for the read-only
base loop device for all overlayed live root filesystems.
Consistently provide a link at /dev/root for wait_for_dev.
Update documentation.
Adjust sysroot.mount configuration for rd.live.overlay.overlayfs option.
Use link at /dev/root as a consistent flag for wait_for_dev.
Adjust documentation.
The old code used /tmp/net.$netif.resolv.conf with $netif being randomly
chosen.
As it is not known which nameserver have which priority, just sort them
and deduplicate.
Daniel Molkentin