Skip test_socket.test_sha256() on linux < 4.5 (GH-4643) (#4645)

bpo-31705.
(cherry picked from commit 86afc1f)

Author: miss-islington

Lib/test/test_socket.py

@@ -5419,6 +5419,9 @@ def create_alg(self, typ, name):
         else:
             return sock
 
+    # bpo-31705: On kernel older than 4.5, sendto() failed with ENOKEY,
+    # at least on ppc64le architecture
+    @support.requires_linux_version(4, 5)
     def test_sha256(self):
         expected = bytes.fromhex("ba7816bf8f01cfea414140de5dae2223b00361a396"
                                  "177a9cb410ff61f20015ad")

Misc/NEWS.d/next/Tests/2017-11-30-12-27-10.bpo-31705.yULW7O.rst

@@ -0,0 +1,3 @@
+Skip test_socket.test_sha256() on Linux kernel older than 4.5. The test
+fails with ENOKEY on kernel 3.10 (on ppc64le). A fix was merged into the
+kernel 4.5.