could not build the referers_hash

[Ryan Brown]

> There is configuration directive to adjust this,
> referer_hash_bucket_size.  You don't need to edit the code.
>
> Maxim Dounin

I got caught by this bug too,

Seems a bit strange why the defaults (if not set) complains that its
not enough.. I can see why people edit the code directly.

If 64 isn't clearly enough when referer_hash_bucket_size isn't set,
why not just up the default to 128 to avoid this unnecessary complaint
by nginx.