diff --git a/Lib/test/regrtest.py b/Lib/test/regrtest.py
index 33a2248..c2a279f 100755
--- a/Lib/test/regrtest.py
+++ b/Lib/test/regrtest.py
@@ -159,6 +159,8 @@
 import unittest
 from inspect import isabstract
 import tempfile
+import platform
+import sysconfig
 
 # Some times __path__ and __file__ are not absolute (e.g. while running from
 # Lib/) and, if we change the CWD to run the tests in a temporary dir, some
@@ -386,6 +388,9 @@
         usage(2, "-T and -j don't go together!")
     if use_mp and findleaks:
         usage(2, "-l and -j don't go together!")
+    if use_mp and max(sys.flags):
+        # TODO: inherit the environment and the flags
+        print("Warning: flags and environment variables are ignored with -j option")
 
     good = []
     bad = []
@@ -393,8 +398,11 @@
     resource_denieds = []
     environment_changed = []
 
-    if verbose:
-        print('The CWD is now', os.getcwd())
+    if not quiet:
+        # Print basic platform information
+        print("==", platform.python_implementation(), *sys.version.split())
+        print("==  ", platform.platform(aliased=True))
+        print("==  ", os.getcwd())
 
     if findleaks:
         try:
@@ -429,10 +437,8 @@
         fp.close()
 
     # Strip .py extensions.
-    if args:
-        args = list(map(removepy, args))
-    if tests:
-        tests = list(map(removepy, tests))
+    removepy(args)
+    removepy(tests)
 
     stdtests = STDTESTS[:]
     nottests = NOTTESTS.copy()
@@ -698,16 +704,15 @@
 
 def findtests(testdir=None, stdtests=STDTESTS, nottests=NOTTESTS):
     """Return a list of all applicable test modules."""
-    if not testdir: testdir = findtestdir()
+    testdir = findtestdir(testdir)
     names = os.listdir(testdir)
     tests = []
+    others = set(stdtests) | nottests
     for name in names:
-        if name[:5] == "test_" and name[-3:] == ".py":
-            modname = name[:-3]
-            if modname not in stdtests and modname not in nottests:
-                tests.append(modname)
-    tests.sort()
-    return stdtests + tests
+        modname, ext = os.path.splitext(name)
+        if modname[:5] == "test_" and ext == ".py" and modname not in others:
+            tests.append(modname)
+    return stdtests + sorted(tests)
 
 def runtest(test, verbose, quiet,
             testdir=None, huntrleaks=False, debug=False, use_resources=None):
@@ -865,8 +870,7 @@
 def runtest_inner(test, verbose, quiet,
                   testdir=None, huntrleaks=False, debug=False):
     support.unload(test)
-    if not testdir:
-        testdir = findtestdir()
+    testdir = findtestdir(testdir)
 
     test_time = 0.0
     refleak = False  # True if the test leaked references.
@@ -1087,18 +1091,16 @@
     for i in range(256):
         s[i:i+1]
 
-def findtestdir():
-    if __name__ == '__main__':
-        file = sys.argv[0]
-    else:
-        file = __file__
-    testdir = os.path.dirname(file) or os.curdir
-    return testdir
+def findtestdir(path=None):
+    return path or os.path.dirname(__file__) or os.curdir
 
-def removepy(name):
-    if name.endswith(".py"):
-        name = name[:-3]
-    return name
+def removepy(names):
+    if not names:
+        return
+    for idx, name in enumerate(names):
+        basename, ext = os.path.splitext(name)
+        if ext == '.py':
+            names[idx] = basename
 
 def count(n, word):
     if n == 1:
@@ -1116,7 +1118,7 @@
 
     from textwrap import fill
     blanks = ' ' * indent
-    print(fill(' '.join(map(str, x)), width,
+    print(fill(' '.join(str(elt) for elt in x), width,
                initial_indent=blanks, subsequent_indent=blanks))
 
 # Map sys.platform to a string containing the basenames of tests
@@ -1432,31 +1434,25 @@
         return self.expected
 
 if __name__ == '__main__':
-    # Remove regrtest.py's own directory from the module search path.  This
-    # prevents relative imports from working, and relative imports will screw
-    # up the testing framework.  E.g. if both test.support and
-    # support are imported, they will not contain the same globals, and
-    # much of the testing framework relies on the globals in the
-    # test.support module.
-    mydir = os.path.abspath(os.path.normpath(os.path.dirname(sys.argv[0])))
-    i = len(sys.path)
-    while i >= 0:
-        i -= 1
-        if os.path.abspath(os.path.normpath(sys.path[i])) == mydir:
-            del sys.path[i]
+    # Simplification for findtestdir().
+    assert __file__ == os.path.abspath(sys.argv[0])
 
-    # findtestdir() gets the dirname out of sys.argv[0], so we have to make it
-    # absolute before changing the CWD.
-    if sys.argv[0]:
-        sys.argv[0] = os.path.abspath(sys.argv[0])
-
+    # When tests are run from the Python build directory, it is best practice
+    # to keep the test files in a subfolder.  It eases the cleanup of leftover
+    # files using command "make distclean".
+    if sysconfig.is_python_build():
+        parent_dir = os.path.join(sysconfig.get_config_var('srcdir'), 'build')
+        if not os.path.exists(parent_dir):
+            os.mkdir(parent_dir)
+    else:
+        parent_dir = os.path.abspath(tempfile.gettempdir())
 
     # Define a writable temp dir that will be used as cwd while running
     # the tests. The name of the dir includes the pid to allow parallel
     # testing (see the -j option).
     TESTCWD = 'test_python_{}'.format(os.getpid())
 
-    TESTCWD = os.path.abspath(os.path.join(tempfile.gettempdir(), TESTCWD))
+    TESTCWD = os.path.join(parent_dir, TESTCWD)
 
     # Run the tests in a context manager that temporary changes the CWD to a
     # temporary and writable directory. If it's not possible to create or