gnupg: vendor SKS patch

This quickly became a 404 upstream.

Fixes https://github.com/NixOS/nixpkgs/64256.

pkgs/tools/security/gnupg/0001-dirmngr-Only-use-SKS-pool-CA-for-SKS-pool.patch

@@ -0,0 +1,34 @@
+From 1c9cc97e9d47d73763810dcb4a36b6cdf31a2254 Mon Sep 17 00:00:00 2001
+From: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
+Date: Sun, 30 Jun 2019 11:54:35 -0400
+Subject: [PATCH] dirmngr: Only use SKS pool CA for SKS pool
+
+* dirmngr/http.c (http_session_new): when checking whether the
+keyserver is the HKPS pool, check specifically against the pool name,
+as ./configure might have been used to select a different default
+keyserver.  It makes no sense to apply Kristian's certificate
+authority to anything other than the literal host
+hkps.pool.sks-keyservers.net.
+
+Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
+GnuPG-Bug-Id: 4593
+---
+ dirmngr/http.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/dirmngr/http.c b/dirmngr/http.c
+index 384f2569d..8e5d53939 100644
+--- a/dirmngr/http.c
++++ b/dirmngr/http.c
+@@ -767,7 +767,7 @@ http_session_new (http_session_t *r_session,
+ 
+     is_hkps_pool = (intended_hostname
+                     && !ascii_strcasecmp (intended_hostname,
+-                                          get_default_keyserver (1)));
++                                          "hkps.pool.sks-keyservers.net"));
+ 
+     /* If the user has not specified a CA list, and they are looking
+      * for the hkps pool from sks-keyservers.net, then default to
+-- 
+2.22.0
+

pkgs/tools/security/gnupg/22.nix

@@ -32,10 +32,7 @@ stdenv.mkDerivation rec {
 
   patches = [
     ./fix-libusb-include-path.patch
-    (fetchpatch {
+    ./0001-dirmngr-Only-use-SKS-pool-CA-for-SKS-pool.patch
-      url = https://files.gnupg.net/file/data/qmxjhc6kuja3orybj7st/PHID-FILE-vvzlnw36427pdnug2amc/file;
-      sha256 = "13snxkmlgmvn0rgxh5k2sgxkp5mbxqiznzm45sw649nvs3ccghq8";
-    })
   ];
   postPatch = ''
     sed -i 's,hkps://hkps.pool.sks-keyservers.net,hkps://keys.openpgp.org,g' \