diff --git a/src/_pytest/fixtures.py b/src/_pytest/fixtures.py
index 902904457..53df79d35 100644
--- a/src/_pytest/fixtures.py
+++ b/src/_pytest/fixtures.py
@@ -853,11 +853,9 @@ class FixtureDef(object):
                     exceptions.append(sys.exc_info())
             if exceptions:
                 e = exceptions[0]
-                del (
-                    exceptions
-                )  # ensure we don't keep all frames alive because of the traceback
+                # Ensure to not keep frame references through traceback.
+                del exceptions
                 six.reraise(*e)
-
         finally:
             hook = self._fixturemanager.session.gethookproxy(request.node.fspath)
             hook.pytest_fixture_post_finalizer(fixturedef=self, request=request)
diff --git a/testing/test_pdb.py b/testing/test_pdb.py
index c0ba7159b..bdb7be940 100644
--- a/testing/test_pdb.py
+++ b/testing/test_pdb.py
@@ -817,7 +817,7 @@ class TestPDB(object):
         result.stdout.fnmatch_lines(["*NameError*xxx*", "*1 error*"])
         assert custom_pdb_calls == []
 
-    def test_pdb_custom_cls_with_settrace(self, testdir, monkeypatch):
+    def test_pdb_custom_cls_with_set_trace(self, testdir, monkeypatch):
         testdir.makepyfile(
             custom_pdb="""
             class CustomPdb(object):
@@ -1133,14 +1133,14 @@ def test_pdbcls_via_local_module(testdir):
     p1 = testdir.makepyfile(
         """
         def test():
-            print("before_settrace")
+            print("before_set_trace")
             __import__("pdb").set_trace()
         """,
         mypdb="""
         class Wrapped:
             class MyPdb:
                 def set_trace(self, *args):
-                    print("settrace_called", args)
+                    print("set_trace_called", args)
 
                 def runcall(self, *args, **kwds):
                     print("runcall_called", args, kwds)
@@ -1161,7 +1161,7 @@ def test_pdbcls_via_local_module(testdir):
         str(p1), "--pdbcls=mypdb:Wrapped.MyPdb", syspathinsert=True
     )
     assert result.ret == 0
-    result.stdout.fnmatch_lines(["*settrace_called*", "* 1 passed in *"])
+    result.stdout.fnmatch_lines(["*set_trace_called*", "* 1 passed in *"])
 
     # Ensure that it also works with --trace.
     result = testdir.runpytest(
diff --git a/testing/test_session.py b/testing/test_session.py
index 377b28937..03f30f32b 100644
--- a/testing/test_session.py
+++ b/testing/test_session.py
@@ -171,7 +171,7 @@ class SessionTests(object):
         )
         try:
             reprec = testdir.inline_run(testdir.tmpdir)
-        except pytest.skip.Exception:  # pragma: no covers
+        except pytest.skip.Exception:  # pragma: no cover
             pytest.fail("wrong skipped caught")
         reports = reprec.getreports("pytest_collectreport")
         assert len(reports) == 1