[m-dev.] prepare.sh tests for the wrong thing

[Zoltan Somogyi]

On Sat, 3 Oct 2015 14:51:18 +1000, Paul Bone <paul at bone.id.au> wrote:
> These are almost certainly all intermediate files, and a quick glance at
> your file supports that.  git didn't delete or move them because they're
> unversioned. 

Yes, I know.

> It's probably easiest to remove the boehm_gc directory
> completely and then run ./prepare.

And I did that, before I sent my previous email.

The point of my mail was to request that you should change prepare.sh
to test for the presence/absence of some file that ISN'T left over like this.

Zoltan.