From 64eb9ea670fd4d31e46e41ee397933fcad05886d Mon Sep 17 00:00:00 2001
From: Mark Dickinson <mdickinson@enthought.com>
Date: Thu, 21 Nov 2019 11:50:40 +0000
Subject: [PATCH 1/6] Modify test for new expected behaviour

---
 testing/test_runner.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/testing/test_runner.py b/testing/test_runner.py
index 86e9bddff..301e11898 100644
--- a/testing/test_runner.py
+++ b/testing/test_runner.py
@@ -900,9 +900,9 @@ def test_store_except_info_on_error():
     # The next run should clear the exception info stored by the previous run
     ItemMightRaise.raise_error = False
     runner.pytest_runtest_call(ItemMightRaise())
-    assert sys.last_type is None
-    assert sys.last_value is None
-    assert sys.last_traceback is None
+    assert not hasattr(sys, "last_type")
+    assert not hasattr(sys, "last_value")
+    assert not hasattr(sys, "last_traceback")
 
 
 def test_current_test_env_var(testdir, monkeypatch):

From 2ffbe41ae526b5367fca798e405fceab9bc57228 Mon Sep 17 00:00:00 2001
From: Mark Dickinson <mdickinson@enthought.com>
Date: Thu, 21 Nov 2019 13:06:47 +0000
Subject: [PATCH 2/6] clear sys.last_traceback via del instead of = None

---
 src/_pytest/runner.py | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/_pytest/runner.py b/src/_pytest/runner.py
index c383146c3..67e28e905 100644
--- a/src/_pytest/runner.py
+++ b/src/_pytest/runner.py
@@ -121,7 +121,12 @@ def pytest_runtest_setup(item):
 
 def pytest_runtest_call(item):
     _update_current_test_var(item, "call")
-    sys.last_type, sys.last_value, sys.last_traceback = (None, None, None)
+    try:
+        del sys.last_type
+        del sys.last_value
+        del sys.last_traceback
+    except AttributeError:
+        pass
     try:
         item.runtest()
     except Exception:

From 9d1082bd302832fe7289dfbed53a81a17eccf05c Mon Sep 17 00:00:00 2001
From: Mark Dickinson <mdickinson@enthought.com>
Date: Thu, 21 Nov 2019 13:13:36 +0000
Subject: [PATCH 3/6] Add changelog file.

---
 changelog/6255.bugfix.rst | 3 +++
 1 file changed, 3 insertions(+)
 create mode 100644 changelog/6255.bugfix.rst

diff --git a/changelog/6255.bugfix.rst b/changelog/6255.bugfix.rst
new file mode 100644
index 000000000..831187feb
--- /dev/null
+++ b/changelog/6255.bugfix.rst
@@ -0,0 +1,3 @@
+Clear the ``sys.last_traceback``, ``sys.last_type`` and ``sys.last_value``
+attributes by deleting them instead of setting them to ``None``. This better
+matches the behaviour of the Python standard library.

From 8d686a8e460fe8dd513efe2632481587ce0d4ab9 Mon Sep 17 00:00:00 2001
From: Mark Dickinson <mdickinson@enthought.com>
Date: Thu, 21 Nov 2019 13:14:19 +0000
Subject: [PATCH 4/6] Add self to AUTHORS

---
 AUTHORS | 1 +
 1 file changed, 1 insertion(+)

diff --git a/AUTHORS b/AUTHORS
index 14c465571..6e2f472fe 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -165,6 +165,7 @@ Marcelo Duarte Trevisani
 Marcin Bachry
 Marco Gorelli
 Mark Abramowitz
+Mark Dickinson
 Markus Unterwaditzer
 Martijn Faassen
 Martin Altmayer

From dbb8c146f041b4ffaa704097007d8bb1f160d990 Mon Sep 17 00:00:00 2001
From: Mark Dickinson <mdickinson@enthought.com>
Date: Thu, 21 Nov 2019 13:22:34 +0000
Subject: [PATCH 5/6] Use proper reST attribute markup.

---
 changelog/6255.bugfix.rst | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/changelog/6255.bugfix.rst b/changelog/6255.bugfix.rst
index 831187feb..6eb064ef3 100644
--- a/changelog/6255.bugfix.rst
+++ b/changelog/6255.bugfix.rst
@@ -1,3 +1,4 @@
-Clear the ``sys.last_traceback``, ``sys.last_type`` and ``sys.last_value``
-attributes by deleting them instead of setting them to ``None``. This better
-matches the behaviour of the Python standard library.
+Clear the :py:attr:`sys.last_traceback`, :py:attr:`sys.last_type`
+and :py:attr:`sys.last_value` attributes by deleting them instead
+of setting them to ``None``. This better matches the behaviour of
+the Python standard library.

From 82424c92708ed6fe9fba83ff4cbc3ce128e13494 Mon Sep 17 00:00:00 2001
From: Mark Dickinson <mdickinson@enthought.com>
Date: Thu, 21 Nov 2019 13:37:17 +0000
Subject: [PATCH 6/6] Fix reST markup.

---
 changelog/6255.bugfix.rst | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/changelog/6255.bugfix.rst b/changelog/6255.bugfix.rst
index 6eb064ef3..831187feb 100644
--- a/changelog/6255.bugfix.rst
+++ b/changelog/6255.bugfix.rst
@@ -1,4 +1,3 @@
-Clear the :py:attr:`sys.last_traceback`, :py:attr:`sys.last_type`
-and :py:attr:`sys.last_value` attributes by deleting them instead
-of setting them to ``None``. This better matches the behaviour of
-the Python standard library.
+Clear the ``sys.last_traceback``, ``sys.last_type`` and ``sys.last_value``
+attributes by deleting them instead of setting them to ``None``. This better
+matches the behaviour of the Python standard library.