[deviantart] use fallback for /intermediary/ URLs

instead of checking availability with HEAD requests

CHANGELOG.md

@@ -1,5 +1,7 @@
 # Changelog
 
+## Unreleased
+
 ## 1.17.1 - 2021-03-19
 ### Additions
 - [architizer] add `project` and `firm` extractors ([#1369](https://github.com/mikf/gallery-dl/issues/1369))

gallery_dl/extractor/deviantart.py

@@ -105,7 +105,8 @@ class DeviantartExtractor(Extractor):
                         intermediary, count = re.subn(
                             r"(/f/[^/]+/[^/]+)/v\d+/.*",
                             r"/intermediary\1", content["src"], 1)
-                        if count and self._check_url(intermediary):
+                        if count:
+                            deviation["_fallback"] = (content["src"],)
                             content["src"] = intermediary
                     if self.quality:
                         content["src"] = re.sub(
@@ -282,9 +283,6 @@ class DeviantartExtractor(Extractor):
         if mtype and mtype.startswith("image/"):
             content.update(data)
 
-    def _check_url(self, url):
-        return self.request(url, method="HEAD", fatal=False).status_code < 400
-
     def _limited_request(self, url, **kwargs):
         """Limits HTTP requests to one every 2 seconds"""
         kwargs["fatal"] = None

gallery_dl/version.py

@@ -6,4 +6,4 @@
 # it under the terms of the GNU General Public License version 2 as
 # published by the Free Software Foundation.
 
-__version__ = "1.17.1"
+__version__ = "1.17.2-dev"