Wrong timezone used when TZ environment variable is set to anything

[SeerLite]

This issue is a....

[X ] Bug
[ ] Other kind of issue (Please describe in detail)

Current Behavior

If the environment variable TZ is set to anything (even if it's set to an empty string), i3lock-color uses UTC instead of whatever the system is configured to use.

Expected Behavior

• If the TZ environment variable describes an invalid timezone, then the system timezone is used.
• If the TZ environment variable describes a valid timezone, then that timezone is used.
• If TZ is unset, the system timezone is used (this one works correctly right now).

Reproduction Instructions

Set system timezone to anything other than UTC. For example, I use America/Santiago.
Then:

unset TZ
i3lock --force-clock

will run and use the correct GMT-4 time.
However, if TZ is set to America/Santiago:

export TZ=America/Santiago
i3lock --force-clock

then UTC is used instead.
If TZ is set to anything, both system time and the TZ variable's time is ignored and UTC is used.

export TZ=
i3lock --force-clock

uses UTC too.

Environment

Output of i3lock --version:

i3lock version: i3lock: version 2.13.c.4 © 2010 Michael Stapelberg, © 2015 Cassandra Fox, © 2021 Raymond Li

Where'd you get i3lock-color from?

[ ] AUR package (which one?)
[ ] Built from source yourself
[X] Other (Please describe in detail)

GNU Guix package