[Bug]: --build-shell parameter stops after configuration not download/unpackaging

[llothar]

Checklist

• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a bug that matches the one I want to file, without success.

flatpak-builder version

1.2.2

Flatpak version

1.12.7

How to reproduce

Create a module that fails in the configuration step

Expected Behavior

Just as described in the documentation for --build-shell

"Extract and prepare the sources for the named module,
and then start a shell in a sandbox identical to the one flatpak-builder
would use for building the module. This is useful to debug a module."

Actual Behavior

It doesnt stop after downloading and extracting the sources, but
AFTER the configuration step. And if the configuration step fails there is no
way to get into the build shell and see what the problem is

Either this or the documentation is wrong.
But an implementation as in the documentation makes much more sense.

Additional Information

No response