[sankaku] restore old 'tags' format (#6043)

lowercase + words separated by underscores

gallery_dl/extractor/sankaku.py

@@ -66,7 +66,8 @@ class SankakuExtractor(BooruExtractor):
     def _prepare(self, post):
         post["created_at"] = post["created_at"]["s"]
         post["date"] = text.parse_timestamp(post["created_at"])
-        post["tags"] = [tag["name"] for tag in post["tags"] if tag["name"]]
+        post["tags"] = [tag["name"].lower().replace(" ", "_")
+                        for tag in post["tags"] if tag["name"]]
         post["tag_string"] = " ".join(post["tags"])
         post["_http_validate"] = self._check_expired
 
@@ -79,7 +80,7 @@ class SankakuExtractor(BooruExtractor):
         for tag in post["tags"]:
             name = tag["name"]
             if name:
-                tags[types[tag["type"]]].append(name)
+                tags[types[tag["type"]]].append(name.lower().replace(" ", "_"))
         for key, value in tags.items():
             post["tags_" + key] = value
             post["tag_string_" + key] = " ".join(value)

test/results/sankaku.py

@@ -142,7 +142,7 @@ __tests__ = (
     "#sha1_content": "5e255713cbf0a8e0801dc423563c34d896bb9229",
 
     "id": "y0abGlDOr2o",
-    "notes": [],
+    "notes": (),
     "tags_artist": [
         "bonocho",
     ],
@@ -219,6 +219,12 @@ __tests__ = (
     "tags_general": [
         "key(mangaka)",
         "key(mangaka)",
+        "english_language",
+        "english_language",
+        "high_resolution",
+        "tagme",
+        "very_high_resolution",
+        "large_filesize",
     ],
 },