Notice that, with the approach above, this script just needs one required input (the fallback file) and just generates bootstrap.inc locally (optionally taking a second arg to specify its name or location); this script can then move to live in the same repository as the fallback file, where a makefile can illustrates the natural way to use it by providing a rule that puts the generated file in the sensible place relative to $(CORE), which defaults to core/ with suitably many ../ prefixes.  Generating an autonomous file locally is nice: it lets the user diff it against the existing file before copying it into place.

Ultimately, of course, we should run this script at compile-time to generate the #include-d file, which would no longer be present in git.