PY-38479 Rely on "venv" defaults regarding symlinks when creating virtualenvs

Because we used to call venv.create() function directly in packaging_tool.py when
creating environments we ended up using function's own default unconditionally
creating copies of executables on all platforms, including those where venv itself
creates symlinks (Linux, MacOS). Turned out, it leads to issues with locating
dynamic libraries when one attempts to create a virtualenv with MacOS 10.15 system
Python 3 interpreter. Now we call venv module directly as we already do with "pip"
relying on its default behavior and patching the only command-line flag that we
actually need -- "--without-pip".

GitOrigin-RevId: d65aaa325817933de7121225038a5cf84fa2c77a

python/helpers/packaging_tool.py

@@ -75,17 +75,16 @@ def run_pip(args):
         error_no_pip()
 
 
-def do_pyvenv(path, system_site_packages):
+def do_pyvenv(args):
+    import runpy
+    # We cannot rely on automatic installation of setuptools and pip and
+    # have to bootstrap these packages ourselves, since some distributions
+    # of CPython on Ubuntu and MacOS don't include "ensurepip" module.
+    sys.argv[1:] = ['--without-pip'] + args
     try:
-        import venv
+        runpy.run_module('venv', run_name='__main__', alter_sys=True)
     except ImportError:
         error("Standard Python 'venv' module not found", ERROR_EXCEPTION)
-    # In Python >= 3.4 venv.create() has a new parameter with_pip=False
-    # that allows to automatically install setuptools and pip with the module
-    # ensurepip. Unfortunately, we cannot use this parameter and have to
-    # bootstrap these packages ourselves, since some distributions of CPython
-    # on Ubuntu don't include ensurepip.
-    venv.create(path, system_site_packages=system_site_packages)
 
 
 def do_untar(name):
@@ -162,12 +161,7 @@ def main():
             opts, args = getopt.getopt(sys.argv[2:], '', ['system-site-packages'])
             if len(args) != 1:
                 usage()
-            path = args[0]
-            system_site_packages = False
-            for opt, arg in opts:
-                if opt == '--system-site-packages':
-                    system_site_packages = True
-            do_pyvenv(path, system_site_packages)
+            do_pyvenv(sys.argv[2:])
         else:
             usage()
     except Exception: