python3: fix a race condition in the test_socket.testSockName test

This test uses find_unused_port() which is inherently racey, so retry
it a few times before failing.

[ YOCTO #14840 ]

(From OE-Core rev: efac044cabdbe77556a0b9903595fd602f39ac8d)

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/python/python3/0001-Mitigate-the-race-condition-in-testSockName.patch

@@ -0,0 +1,47 @@
+Upstream-Status: Pending
+Signed-off-by: Ross Burton <ross.burton@arm.com>
+
+From 8103b90148e8768456c3ab707de105d63d9d5b20 Mon Sep 17 00:00:00 2001
+From: Ross Burton <ross.burton@arm.com>
+Date: Fri, 17 Jun 2022 11:53:59 +0100
+Subject: [PATCH] Mitigate the race condition in testSockName
+
+find_unused_port() has an inherent race condition, but we can't use
+bind_port() as that uses .getsockname() which this test is exercising.
+
+Try binding to unused ports a few times before failing.
+---
+ Lib/test/test_socket.py | 15 +++++++++++++--
+ 1 file changed, 13 insertions(+), 2 deletions(-)
+
+diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
+index c981903824..b1630d18b6 100644
+--- a/Lib/test/test_socket.py
++++ b/Lib/test/test_socket.py
+@@ -1390,10 +1390,21 @@ def testStringToIPv6(self):
+ 
+     def testSockName(self):
+         # Testing getsockname()
+-        port = socket_helper.find_unused_port()
+         sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+         self.addCleanup(sock.close)
+-        sock.bind(("0.0.0.0", port))
++
++        # Since find_unused_port() is inherently subject to race conditions, we
++        # call it a couple times if necessary.
++        for i in itertools.count():
++            port = socket_helper.find_unused_port()
++            try:
++                sock.bind(("0.0.0.0", port))
++            except OSError as e:
++                if e.errno != errno.EADDRINUSE or i == 5:
++                    raise
++            else:
++                break
++
+         name = sock.getsockname()
+         # XXX(nnorwitz): http://tinyurl.com/os5jz seems to indicate
+         # it reasonable to get the host's addr in addition to 0.0.0.0.
+-- 
+2.25.1
+