Avoid block parser warning in SmartyPants (#6565)

Merge pull request 6565

test/test_filters.rb

@@ -100,6 +100,10 @@ class TestFilters < JekyllUnitTest
         assert_equal "“", @filter.smartify("&ldquo;")
       end
 
+      should "convert multiple lines" do
+        assert_equal "…\n…", @filter.smartify("...\n...")
+      end
+
       should "allow raw HTML passthrough" do
         assert_equal(
           "Span HTML is <em>not</em> escaped",
@@ -123,6 +127,12 @@ class TestFilters < JekyllUnitTest
           @filter.smartify(404)
         )
       end
+
+      should "not output any warnings" do
+        assert_empty(
+          capture_output { @filter.smartify("Test") }
+        )
+      end
     end
 
     should "sassify with simple string" do