Issue #15300: Ensure the temporary test working directories are in the same parent folder when running tests in multiprocess mode from a Python build.

Patch by Chris Jerdonek.

Lib/test/regrtest.py

@@ -572,10 +572,14 @@ def main(tests=None, testdir=None, verbose=0, quiet=False,
                         output.put((None, None, None, None))
                         return
                     # -E is needed by some tests, e.g. test_import
+                    # Running the child from the same working directory ensures
+                    # that TEMPDIR for the child is the same when
+                    # sysconfig.is_python_build() is true. See issue 15300.
                     popen = Popen(base_cmd + ['--slaveargs', json.dumps(args_tuple)],
                                    stdout=PIPE, stderr=PIPE,
                                    universal_newlines=True,
-                                   close_fds=(os.name != 'nt'))
+                                   close_fds=(os.name != 'nt'),
+                                   cwd=support.SAVEDCWD)
                     stdout, stderr = popen.communicate()
                     # Strip last refcount output line if it exists, since it
                     # comes from the shutdown of the interpreter in the subcommand.

Misc/ACKS

@@ -458,6 +458,7 @@ Zbyszek Jędrzejewski-Szmek
 Drew Jenkins
 Flemming Kjær Jensen
 MunSic Jeong
+Chris Jerdonek
 Orjan Johansen
 Fredrik Johansson
 Gregory K. Johnson

Misc/NEWS

@@ -341,6 +341,10 @@ Extension Modules
 Tests
 -----
 
+- Issue #15300: Ensure the temporary test working directories are in the same
+  parent folder when running tests in multiprocess mode from a Python build.
+  Patch by Chris Jerdonek.
+
 - test_nntplib now tolerates being run from behind NNTP gateways that add
   "X-Antivirus" headers to articles