fix redirection in download tests (#3568)

Co-authored-by: Francisco Massa <fvsmassa@gmail.com>

test/test_datasets_download.py

@@ -14,7 +14,13 @@ import warnings
 import pytest
 
 from torchvision import datasets
-from torchvision.datasets.utils import download_url, check_integrity, download_file_from_google_drive, USER_AGENT
+from torchvision.datasets.utils import (
+    download_url,
+    check_integrity,
+    download_file_from_google_drive,
+    _get_redirect_url,
+    USER_AGENT,
+)
 
 from common_utils import get_tmp_dir
 from fakedata_generation import places365_root
@@ -48,22 +54,28 @@ def limit_requests_per_time(min_secs_between_requests=2.0):
 urlopen = limit_requests_per_time()(urlopen)
 
 
-def resolve_redirects(max_redirects=3):
+def resolve_redirects(max_hops=3):
     def outer_wrapper(fn):
         def inner_wrapper(request, *args, **kwargs):
-            url = initial_url = request.full_url if isinstance(request, Request) else request
+            initial_url = request.full_url if isinstance(request, Request) else request
+            url = _get_redirect_url(initial_url, max_hops=max_hops)
 
-            for _ in range(max_redirects + 1):
-                response = fn(request, *args, **kwargs)
+            if url == initial_url:
+                return fn(request, *args, **kwargs)
 
-                if response.url == url or response.url is None:
-                    if url != initial_url:
-                        warnings.warn(f"The URL {initial_url} ultimately redirects to {url}.")
-                    return response
+            warnings.warn(f"The URL {initial_url} ultimately redirects to {url}.")
 
-                url = response.url
-            else:
-                raise RecursionError(f"Request to {initial_url} exceeded {max_redirects} redirects.")
+            if not isinstance(request, Request):
+                return fn(url, *args, **kwargs)
+
+            request_attrs = {
+                attr: getattr(request, attr) for attr in ("data", "headers", "origin_req_host", "unverifiable")
+            }
+            # the 'method' attribute does only exist if the request was created with it
+            if hasattr(request, "method"):
+                request_attrs["method"] = request.method
+
+            return fn(Request(url, **request_attrs), *args, **kwargs)
 
         return inner_wrapper
 
@@ -150,7 +162,7 @@ def assert_server_response_ok():
 
 
 def assert_url_is_accessible(url, timeout=5.0):
-    request = Request(url, headers={"method": "HEAD", "User-Agent": USER_AGENT})
+    request = Request(url, headers={"User-Agent": USER_AGENT}, method="HEAD")
     with assert_server_response_ok():
         urlopen(request, timeout=timeout)