Note that I wasn't able to reproduce the failure
Hmm, why not? The only reason I can think for the build to work in Salsa CI is that the chroot used by Salsa CI includes (improperly!) packages which are not build essential (tzdata-legacy, in this case). You might want to ensure (as maintainer of Salsa CI) that such thing does not happen (or, at the very minimum, document the differences between a completely clean chroot and the one used by Salsa CI). If you are going to add tzdata-legacy, I would much prefer that you do so because you can also reproduce the problem, not just because you believe it's "relatively safe". Note that in the past debootstrap installed more packages in a chroot than those mandated by Debian Policy, but this was fixed a year ago and the trixie/sid version of debootstrap does finally the right thing. Thanks.
