two reasons:

* `search_file` lives in `filetools.py`, and `config.py` imports from `filetools.py`, so accessing the build options via `config.py` would result in a cyclic dependency between `config.py` and `filetools.py`; no other `filetools` function use build options in any way, this was the only one
* the only location where `search_file` is used is in `main.py`, where the build options are set, so there's direct access there

I agree the latter is a bit lame, but the first reason is the one that really made me refactor it to keep using `search_file` from using `build_options`.