util.cache: Keep eviction candidate if callback resized to make room

Previously either the old or the new values would be rejected, even if
the cache was resized to allow more items.

spec/util_cache_spec.lua

@@ -388,5 +388,26 @@ describe("util.cache", function()
 			c:resize(3);
 			assert.same({"v5", "v4", "v3"}, vs(c));
 		end);
+
+		it("eviction stuff", function ()
+			local c;
+			c = cache.new(4, function(_k,_v)
+				if c.size < 10 then
+					c:resize(c.size*2);
+				end
+			end)
+			for i = 1,20 do
+				c:set(i,i)
+			end
+			assert.equal(16, c.size);
+			assert.is_nil(c:get(1))
+			assert.is_nil(c:get(4))
+			assert.equal(5, c:get(5))
+			assert.equal(20, c:get(20))
+			c:resize(4)
+			assert.equal(20, c:get(20))
+			assert.equal(17, c:get(17))
+			assert.is_nil(c:get(10))
+		end)
 	end);
 end);