python-3.6.zip added from Github

README.cosmo contains the necessary links.

third_party/python/Lib/test/regrtest.py

@@ -0,0 +1,50 @@
+#! /usr/bin/env python3
+
+"""
+Script to run Python regression tests.
+
+Run this script with -h or --help for documentation.
+"""
+
+# We import importlib *ASAP* in order to test #15386
+import importlib
+
+import os
+import sys
+from test.libregrtest import main
+
+
+# Alias for backward compatibility (just in case)
+main_in_temp_cwd = main
+
+
+def _main():
+    global __file__
+
+    # Remove regrtest.py's own directory from the module search path. Despite
+    # the elimination of implicit relative imports, this is still needed to
+    # ensure that submodules of the test package do not inappropriately appear
+    # as top-level modules even when people (or buildbots!) invoke regrtest.py
+    # directly instead of using the -m switch
+    mydir = os.path.abspath(os.path.normpath(os.path.dirname(sys.argv[0])))
+    i = len(sys.path) - 1
+    while i >= 0:
+        if os.path.abspath(os.path.normpath(sys.path[i])) == mydir:
+            del sys.path[i]
+        else:
+            i -= 1
+
+    # findtestdir() gets the dirname out of __file__, so we have to make it
+    # absolute before changing the working directory.
+    # For example __file__ may be relative when running trace or profile.
+    # See issue #9323.
+    __file__ = os.path.abspath(__file__)
+
+    # sanity check
+    assert __file__ == os.path.abspath(sys.argv[0])
+
+    main()
+
+
+if __name__ == '__main__':
+    _main()