sbuild workflow creates sbuild work requests with imprecise environment match

Since we started creating dedicated lintian environments, the sbuild work requests created by the sbuild workflow tend to fail e.g. https://debusine.freexian.com/freexian/elts/work-request/9062/. The workflow template does not define the sbuild environment. The sbuild workflow https://debusine.freexian.com/freexian/elts/work-request/9063/ has target_distribution: freexian:stretch, which looks reasonable. Moving to the created sbuild work requests https://debusine.freexian.com/freexian/elts/work-request/9064/, the environment is selected as freexian/match:codename=stretch. This will also match lintian environments and is what ends up being used. The lintian environments on debusine.f.c are unsuitable for building as they lack the apt package.

How can we match the sbuild environments in a more useful way?