Now this is ugly: instead of commoditizing the repetitive code
the result ended up working differently by creating several
repositories for the target subdirs instead of the single one
for the generated subprofile as a whole.

This results in .disk/profile.tgz being basically useless
in every image since c4311108.

There were heaps of "if type -t git" there already;
it wasn't an unintentional mishap but rather a moderate
copy-paste to get the use cases, and now these seem to
have essentially settled.

So time to scrap some dups.

NB: the scripts in the generated profile can't rely on
the contents of the metaprofile (these need to be able
to work in standalone case either), so a bit of crap
still lurks there.