ezjail-admin(8) is very clear about
ezjail-admin update
.
So you got it wrong.
These lines are generated because jails use the kernel of the jail-host, thus no kernel can be installed in a jail (in contrast to other virtualization methods). So the "spurious lines" can be ignored.
I think we are saying the same thing.
From the manual:
=========
To upgrade the basejail to a new version, first upgrade the host system as described in Section 23.2.3, “Performing Major and Minor Version Upgrades”. Once the host has been upgraded and rebooted, the basejail can then be upgraded. freebsd-update(8) has no way of determining which version is currently installed in the basejail, so the
original version must be specified. Use file(1) to determine the original version in the basejail:
#
file /usr/jails/basejail/bin/sh
/usr/jails/basejail/bin/sh: ELF 64-bit LSB executable, x86-64, version 1 (FreeBSD), ↺ dynamically linked (uses shared libs), for FreeBSD 9.3, stripped
Now use this information to perform the upgrade
from 9.3-RELEASE to the current version of the host system:
#ezjail-adminupdate-U -s 9.3-RELEASE
=========
So this
ezjail-adminupdate-U -s 9.3-RELEASE
would upgrade the base jail from 9.3-RELEASE to whatever the current host version (10.1, etc.) is.
The OP was going from 10.1 to 10.2, so he would
# file /usr/jails/basejail/bin/sh
and get a 10.1-RELEASE for the basejail and then pass that version to
# ezjail-adminupdate-U -s 10.1-RELEASE
In the -U case: Pass this release tag to freebsd-update(8) as the source OS version of the basejail.
So the OP would have 10.1-RELEASE in his basejail, correct? So to upgrade the basejail he would pass that 10.1-RELEASE with the -s option. Sidetone instructs the OP to pass a 10.2-RELEASE with the -s option.
So to upgrade a 10.1-RELEASE basejail to 10.2, which gets passed with the -s option?