nose: clean up, support Python 3.10. (#8825)

Due to changes in setuptools, we need to run 2to3 ourselves.
While we're at it, lets apply relevant patches from Debian.

https://salsa.debian.org/python-team/packages/nose/

dev-python/nose/patches/debian/disable-unstable-tests.diff

@@ -0,0 +1,49 @@
+From: Dmitry Shachnev <mitya57@gmail.com>
+Date: Thu, 8 Oct 2015 10:02:00 -0700
+Subject: Disable some unstable tests in multiprocessing module
+
+Forwarded: not-needed
+Last-Update: 2014-05-04
+---
+ functional_tests/test_multiprocessing/test_keyboardinterrupt.py | 2 ++
+ functional_tests/test_multiprocessing/test_process_timeout.py   | 2 ++
+ 2 files changed, 4 insertions(+)
+
+diff --git a/functional_tests/test_multiprocessing/test_keyboardinterrupt.py b/functional_tests/test_multiprocessing/test_keyboardinterrupt.py
+index 18c8af1..aead7e2 100644
+--- a/functional_tests/test_multiprocessing/test_keyboardinterrupt.py
++++ b/functional_tests/test_multiprocessing/test_keyboardinterrupt.py
+@@ -63,6 +63,7 @@ def get_log_content(logfile):
+     return content
+ 
+ def test_keyboardinterrupt():
++    raise nose.SkipTest('Disabled in Debian')
+     process, logfile, _ = keyboardinterrupt('keyboardinterrupt.py')
+     stdout, stderr = [s.decode('utf-8') for s in process.communicate(None)]
+     log = get_log_content(logfile)
+@@ -83,6 +84,7 @@ def test_keyboardinterrupt():
+ 
+ 
+ def test_keyboardinterrupt_twice():
++    raise nose.SkipTest('Disabled in Debian')
+     process, logfile, killfile = keyboardinterrupt('keyboardinterrupt_twice.py')
+     waitForKillFile(killfile)
+     os.killpg(process.pid, signal.SIGINT)
+diff --git a/functional_tests/test_multiprocessing/test_process_timeout.py b/functional_tests/test_multiprocessing/test_process_timeout.py
+index 6b858f8..73b4e3b 100644
+--- a/functional_tests/test_multiprocessing/test_process_timeout.py
++++ b/functional_tests/test_multiprocessing/test_process_timeout.py
+@@ -1,4 +1,5 @@
+ import os
++import nose
+ 
+ from test_multiprocessing import MPTestBase
+ 
+@@ -7,6 +8,7 @@ class TestMPTimeout(MPTestBase):
+     suitepath = os.path.join(os.path.dirname(__file__), 'support', 'timeout.py')
+ 
+     def runTest(self):
++        raise nose.SkipTest('Disabled in Debian')
+         assert "TimedOutException: 'timeout.test_timeout'" in self.output
+         assert "Ran 2 tests in" in self.output
+         assert "FAILED (errors=1)" in self.output