I get this error if I define a 'MASTER_SITE_OVERRIDE' in /etc/mk.conf.
Looking at bsd.pkg.mk I don't see how PATCH_SITES is used differently
than MASTER_SITES, yet that doesn't generate an error.  Package distfiles
are fetched ok, then the error is generated.

-Andrew
-- 
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Andrew Gillham                            | This space left blank
gillham@whirlpool.com                     | inadvertently.
I speak for myself, not for my employer.  | Contact the publisher.