tests: minor sys.path cleanup

Author: blueyed

testing/python/collect.py

@@ -34,8 +34,6 @@ def test_import_duplicate(self, testdir):
         )
 
     def test_import_prepend_append(self, testdir, monkeypatch):
-        syspath = list(sys.path)
-        monkeypatch.setattr(sys, "path", syspath)
         root1 = testdir.mkdir("root1")
         root2 = testdir.mkdir("root2")
         root1.ensure("x456.py")

testing/test_assertrewrite.py

@@ -1335,7 +1335,7 @@ def test_cwd_changed(self, testdir, monkeypatch):
         # Setup conditions for py's fspath trying to import pathlib on py34
         # always (previously triggered via xdist only).
         # Ref: https://github.com/pytest-dev/py/pull/207
-        monkeypatch.setattr(sys, "path", [""] + sys.path)
+        monkeypatch.syspath_prepend("")
         monkeypatch.delitem(sys.modules, "pathlib", raising=False)
 
         testdir.makepyfile(