bpo-46678: Fix Invalid cross device link in Lib/test/support/import_helper.py (GH-31204) (GH-31207)

In `Lib/test/support/import_helper.py`, the function `make_legacy_pyc` makes a call to `os.rename` which can fail when the source and target live on different devices. This happens (for example) when `PYTHONPYCACHEPREFIX` is set to a directory anywhere on disk, while a ramdisk is mounted on `/tmp` (the latter of which is the default on various Linux distros). Replacing `os.rename` with `shutil.move` fixes this.

Automerge-Triggered-By: GH:brettcannon
(cherry picked from commit da576e0)

Co-authored-by: Jason Wilkes <[email protected]>

Author: miss-islington

Lib/test/support/import_helper.py

@@ -2,6 +2,7 @@
 import importlib
 import importlib.util
 import os
+import shutil
 import sys
 import unittest
 import warnings
@@ -58,7 +59,7 @@ def make_legacy_pyc(source):
     pyc_file = importlib.util.cache_from_source(source)
     up_one = os.path.dirname(os.path.abspath(source))
     legacy_pyc = os.path.join(up_one, source + 'c')
-    os.rename(pyc_file, legacy_pyc)
+    shutil.move(pyc_file, legacy_pyc)
     return legacy_pyc
 
 

Misc/NEWS.d/next/Tests/2022-02-07-12-40-45.bpo-46678.zfOrgL.rst

@@ -0,0 +1,3 @@
+The function ``make_legacy_pyc`` in ``Lib/test/support/import_helper.py`` no
+longer fails when ``PYTHONPYCACHEPREFIX`` is set to a directory on a
+different device from where tempfiles are stored.