test(images): enable test for refusal to upscale thumbnail

This test should have been enabled when PR lektor#960 was merged.

tests/demo-project/templates/page.html

@@ -25,7 +25,9 @@ <h1>{{ this.title }}</h1>
 
     {# larger than original#}
     {% set t0 = img.thumbnail(400, 600, upscale=True) %}
-    <img alt="original" src="{{ t0|url }}" width="{{ t0.width }}" height="{{ t0.height }}">
+    <img alt="upscaled" src="{{ t0|url }}" width="{{ t0.width }}" height="{{ t0.height }}">
+    {% set t1 = img.thumbnail(400, 600, upscale=False) %}
+    <img alt="original" src="{{ t1|url }}" width="{{ t1.width }}" height="{{ t1.height }}">
   {% endfor %}
 
   {# Not all subpages have a video clip, so we test for that here #}

tests/test_images.py

@@ -203,16 +203,14 @@ def test_thumbnail_quality(builder):
     assert image_size < 9200
 
 
-# TODO: delete this when the thumbnails backwards-compatibility period ends
-@pytest.mark.skip(reason="future behaviour")
 def test_large_thumbnail_returns_original(builder):
     builder.build_all()
     with open(
         os.path.join(builder.destination_path, "index.html"), encoding="utf-8"
     ) as f:
         html = f.read()
 
-    assert '<img alt="original" src="./test.jpg" width="384" height="512">' in html
+    assert '<img alt="original" src="test.jpg" width="384" height="512">' in html
 
 
 def test_dimensions():