gh-99730: urllib.request: Keep HEAD method on redirect (GH-99731)

Author: haampie

Lib/test/test_urllib2.py

@@ -1402,6 +1402,15 @@ def http_open(self, req):
                 request = handler.last_buf
                 self.assertTrue(request.startswith(expected), repr(request))
 
+    def test_redirect_head_request(self):
+        from_url = "http://example.com/a.html"
+        to_url = "http://example.com/b.html"
+        h = urllib.request.HTTPRedirectHandler()
+        req = Request(from_url, method="HEAD")
+        fp = MockFile()
+        new_req = h.redirect_request(req, fp, 302, "Found", {}, to_url)
+        self.assertEqual(new_req.get_method(), "HEAD")
+
     def test_proxy(self):
         u = "proxy.example.com:3128"
         for d in dict(http=u), dict(HTTP=u):

Lib/urllib/request.py

@@ -650,6 +650,7 @@ def redirect_request(self, req, fp, code, msg, headers, newurl):
         newheaders = {k: v for k, v in req.headers.items()
                       if k.lower() not in CONTENT_HEADERS}
         return Request(newurl,
+                       method="HEAD" if m == "HEAD" else "GET",
                        headers=newheaders,
                        origin_req_host=req.origin_req_host,
                        unverifiable=True)

Misc/NEWS.d/next/Library/2022-11-23-17-16-31.gh-issue-99730.bDQdaX.rst

@@ -0,0 +1 @@
+HEAD requests are no longer upgraded to GET request during redirects in urllib.