Running tectonic -X bundle search with custom ttb bundle does not list any files

Running the command

`tectonic -X bundle search` using a custom-built bundle based on texlive2024-0312 does not print out any files.

This functionality seems to be important in the following really cool project, the non-custom tectonic build of the texpresso project. https://github.com/let-def/texpresso/tree/detectonic