rust-coreutils date is unable to parse UTC date

Background

During the installation of tzdata the package run the following commands

	# Show the new setting to the user
	UTdate=$(LC_ALL=C TZ=UTC0 date)

	TZdate=$(unset TZ ; LANG=C date -d "$UTdate")
	echo "Local time is now:      $TZdate."
	echo "Universal Time is now:  $UTdate."
	if [ -z "$DEBCONF_RECONFIGURE" ] ; then
		echo "Run 'dpkg-reconfigure tzdata' if you wish to change it."
	fi
	echo

as result, an error is triggered

2025/04/28 12:08:59 debootstrap.log | Setting up tzdata (2025b-2+apertis0bv2026dev2b1) ...
2025/04/28 12:08:59 debootstrap.log | 
2025/04/28 12:08:59 debootstrap.log | Current default time zone: 'Etc/UTC'
2025/04/28 12:08:59 debootstrap.log | date: invalid date 'Mon Apr 28 12:08:57 UTC 2025'
2025/04/28 12:08:59 debootstrap.log | dpkg: error processing package tzdata (--configure):
2025/04/28 12:08:59 debootstrap.log |  installed tzdata package post-installation script subprocess returned error exit status 1

https://gitlab.apertis.org/infrastructure/apertis-docker-images/-/jobs/4160587/raw

After investigating, the "UTC" mention in the argument triggers the error. The related code can be found at https://gitlab.apertis.org/pkg/rust-coreutils/-/blob/apertis/v2026dev2/src/uu/date/src/date.rs?ref_type=heads#L301

This has become an issue since now rust-coreutils date sets the exit code properly, causing the configure step in tzdata to fail.

Reproducibility

How often the issue is hit when repeating the steps to reproduce and changing nothing?

Put the in the most appropriate entry:

1. ✅ always
2. often, but not always
3. rarely

Impact of bug

Due to this issue it is not possible to bootstrap v2026dev2.

Outcomes

• pkg/tzdata!75 (merged) (workaround)

Management data

This section is for management only, it should be the last one in the description.

/cc @em @balasubramanian @sudarshan @wlozano

Phabricator link: https://phabricator.apertis.org/T11017