Reported by Andreas Enge <andreas@enge.fr>.
* nix/sync-with-upstream: Expand use of {cc,hh}, to placate dash.
# context is expected to truly copy the underlying hash context. The copy
# constructor cannot be used in 'Ctx' if that's a union, so turn it into a
# structure (we can afford to two wasted words.)
-sed -i "$top_srcdir/nix/libutil/hash".{cc,hh} \
+sed -i "$top_srcdir/nix/libutil/hash.cc" "$top_srcdir/nix/libutil/hash.hh" \
-e 's|union Ctx|struct Ctx|g'