[pixiv] provide fallback URLs (#6762)

test/results/pixiv.py

@@ -289,6 +289,15 @@ __tests__ = (
     "caption": r"re:Either she doesn't know how to pose or she can't move with that much clothing on her, in any case she's very well dressed for a holiday trip around town. Lots of stuff to see and a perfect day to grab some sweet pastries at the bakery.<br />...",
 },
 
+{
+    "#url"     : "https://www.pixiv.net/artworks/56360615",
+    "#comment" : "fallback; 'original' version results in HTTP 500 error (#6762)",
+    "#class"   : pixiv.PixivWorkExtractor,
+    "#options" : {"retries": 0},
+    "#range"   : "4",
+    "#sha1_content": "aa119c27fec0a36bbd06e7491987acf5f1be6293",
+},
+
 {
     "#url"     : "https://www.pixiv.net/en/artworks/966412",
     "#category": ("", "pixiv", "work"),