[reddit] fix '/external-preview' embed downloads (#9037)

don't strip URL parameters

gallery_dl/extractor/reddit.py

@@ -215,7 +215,10 @@ class RedditExtractor(Extractor):
 
             if src := data.get("s"):
                 if url := src.get("u") or src.get("gif") or src.get("mp4"):
-                    yield url.partition("?")[0].replace("/preview.", "/i.", 1)
+                    if "//external" not in url:
+                        url = url.partition("?")[0].replace(
+                            "/preview.", "/i.", 1)
+                    yield url
                 else:
                     self.log.error(
                         "embed %s: unable to fetch download URL for item %s",

test/results/reddit.py

@@ -303,6 +303,16 @@ __tests__ = (
     "#results" : "ytdl:https://v.redd.it/link/1n260wh/asset/8q50b220tplf1/DASHPlaylist.mpd?a=1759085227%2CYTU2NGJjNTlmNjBlOGE2NWUwYWI0MjRjZDYzZjllZjk4Nzc3Y2Y4Nzc1NDMzOTBkYTNkOWFjOGMzZjUzZDAzMQ%3D%3D&v=1&f=sd",
 },
 
+{
+    "#url"     : "https://www.reddit.com/r/vi/comments/1qi6tev/comment/o0v9zh8/",
+    "#comment" : "'external-preview' embed",
+    "#class"   : reddit.RedditSubmissionExtractor,
+    "#options" : {"comments": 100},
+    "#range"   : "2",
+    "#pattern" : r"https://external-preview.redd.it/0DT-wjorv2NNSSoTW-62QG4xs7ZqGE2jcn2OEa2Xnks\.gif\?width=200&height=200&s=\w+",
+    "#sha1_content": "5014a016d7d5fb2c9fdaa01f0b43afeff158cd9b",
+},
+
 {
     "#url"     : "https://i.redd.it/upjtjcx2npzz.jpg",
     "#category": ("", "reddit", "image"),