Ævar Arnfjörð Bjarmason [off-list ref] writes:

Add "const" to the "struct module_clone_data" that we pass to
clone_submodule(), which makes the ownership clear, and stops us from
clobbering the "clone_data->path".

We still need to add to the "reference" member, which is a "struct
string_list". Let's do this by having clone_submodule() create its
own, and copy the contents over, allowing us to pass it as a
separate parameter.

I can't help but think that this would be easier to review as part of
the leaks series since:

- Outside of leaks, I don't think we really care about ownership (though
  please please correct me if I'm off base).

- The ownership of "reference" is still quite messy (downstream code
  might append to it, but its members are sometimes free()-able and
  sometimes not), so it's hard to visualize what we're getting out of
  this change without seeing the corresponding leak fix.

and...

- (this is pretty minor) It feels weird to see that we're intentionally
  leaking clone_data_path at its inception. We aren't introducing any
  new leaks, but moving this to the leaks series makes it clearer that
  we eventually do the right thing.