When no zoneinfo data is present on the running system, but is present in a chroot environment, tzsetup -C incorrectly displays the message "Does the abbreviation 'UTC' look reasonable?" regardless of the time zone selected. tzsetup does not do a chroot(2) system call. Instead, it simulates the effect by prefixing all paths with the chroot environment. The problem is that when tzsetup is going to verify your configuration, it would use tzset(3), which does not respect the simulated chroot effect. When no zoneinfo data is present, everything would be considered as UTC.
Fixed in -HEAD as r289269.
A commit references this bug: Author: delphij Date: Tue Oct 13 22:55:17 UTC 2015 New revision: 289269 URL: https://svnweb.freebsd.org/changeset/base/289269 Log: Use chroot(2) instead of using prefixes for files. Previously, the code prefixes the chroot path to actual file paths to simulate the effect. This, however, will not work for tzset(3) which expects the current system have a working set of timezone data files, and that is not always the case. This changeset simplifies the handling of paths and use an actual chroot(2) call to implement the effect. PR: bin/197313 MFC after: 2 weeks Changes: head/usr.sbin/tzsetup/tzsetup.c
A commit references this bug: Author: delphij Date: Tue Oct 27 00:37:19 UTC 2015 New revision: 290027 URL: https://svnweb.freebsd.org/changeset/base/290027 Log: MFC r289269: Use chroot(2) instead of using prefixes for files. Previously, the code prefixes the chroot path to actual file paths to simulate the effect. This, however, will not work for tzset(3) which expects the current system have a working set of timezone data files, and that is not always the case. This changeset simplifies the handling of paths and use an actual chroot(2) call to implement the effect. PR: bin/197313 Changes: _U stable/10/ stable/10/usr.sbin/tzsetup/tzsetup.c
This have been merged to stable/10, thanks for notifying.