Disable coverage inside test_chained_exceptions_no_reprcrash

Seeing this error in Python 3.5 on Windows:

   File "d:\a\pytest\pytest\.tox\py35-xdist\lib\site-packages\coverage\sqldata.py", line 1078, in executescript
     self.con.executescript(script)
   sqlite3.OperationalError: database schema has changed

Workaround that by disabling coverage while running the sub test
in test_chained_exceptions_no_reprcrash

Author: nicoddemus

testing/test_reports.py

@@ -1,3 +1,5 @@
+import sys
+
 import pytest
 from _pytest._code.code import ExceptionChainRepr
 from _pytest.pathlib import Path
@@ -314,9 +316,7 @@ def check_longrepr(longrepr):
         # elsewhere and we do check the contents of the longrepr object after loading it.
         loaded_report.longrepr.toterminal(tw_mock)
 
-    def test_chained_exceptions_no_reprcrash(
-        self, testdir, tw_mock,
-    ):
+    def test_chained_exceptions_no_reprcrash(self, testdir, tw_mock, monkeypatch):
         """Regression test for tracebacks without a reprcrash (#5971)
 
         This happens notably on exceptions raised by multiprocess.pool: the exception transfer
@@ -335,7 +335,17 @@ def test_a():
                     p.submit(func).result()
         """
         )
+        # somehow on Python 3.5 the build fails with:
+        #   File "d:\a\pytest\pytest\.tox\py35-xdist\lib\site-packages\coverage\sqldata.py", line 1078, in executescript
+        #     self.con.executescript(script)
+        #   sqlite3.OperationalError: database schema has changed
+        # disable coverage while running the sub test
+        is_py35_win = sys.version_info <= (3, 5) and sys.platform.startswith("win")
+        if is_py35_win:
+            monkeypatch.delenv("COVERAGE_PROCESS_START", raising=False)
         reprec = testdir.inline_run()
+        if is_py35_win:
+            monkeypatch.undo()
 
         reports = reprec.getreports("pytest_runtest_logreport")