bpo-34977: Use venv redirector instead of original python.exe on Windows (GH-11029)

2 files changed, 20 insertions, 7 deletions

diff --git a/Doc/library/venv.rst b/Doc/library/venv.rst
index 7058d3a..efa51e2 100644
--- a/Doc/library/venv.rst
+++ b/Doc/library/venv.rst
@@ -130,7 +130,6 @@ creation according to their needs, the :class:`EnvBuilder` class.
     .. versionadded:: 3.6
        Added the ``prompt`` parameter
 
-
     Creators of third-party virtual environment tools will be free to use the
     provided ``EnvBuilder`` class as a base class.
 
@@ -177,16 +176,15 @@ creation according to their needs, the :class:`EnvBuilder` class.
 
     .. method:: setup_python(context)
 
-        Creates a copy of the Python executable (and, under Windows, DLLs) in
-        the environment. On a POSIX system, if a specific executable
-        ``python3.x`` was used, symlinks to ``python`` and ``python3`` will be
-        created pointing to that executable, unless files with those names
-        already exist.
+        Creates a copy of the Python executable in the environment on POSIX
+        systems. If a specific executable ``python3.x`` was used, symlinks to
+        ``python`` and ``python3`` will be created pointing to that executable,
+        unless files with those names already exist.
 
     .. method:: setup_scripts(context)
 
         Installs activation scripts appropriate to the platform into the virtual
-        environment.
+        environment. On Windows, also installs the ``python[w].exe`` scripts.
 
     .. method:: post_setup(context)
 
@@ -194,6 +192,11 @@ creation according to their needs, the :class:`EnvBuilder` class.
         implementations to pre-install packages in the virtual environment or
         perform other post-creation steps.
 
+    .. versionchanged:: 3.7.2
+       Windows now uses redirector scripts for ``python[w].exe`` instead of
+       copying the actual binaries, and so :meth:`setup_python` does nothing
+       unless running from a build in the source tree.
+
     In addition, :class:`EnvBuilder` provides this utility method that can be
     called from :meth:`setup_scripts` or :meth:`post_setup` in subclasses to
     assist in installing custom scripts into the virtual environment.
diff --git a/Doc/whatsnew/3.7.rst b/Doc/whatsnew/3.7.rst
index 8b9b64f..3e94a61 100644
--- a/Doc/whatsnew/3.7.rst
+++ b/Doc/whatsnew/3.7.rst
@@ -2512,3 +2512,13 @@ In 3.7.1 the :mod:`tokenize` module now implicitly emits a ``NEWLINE`` token
 when provided with input that does not have a trailing new line.  This behavior
 now matches what the C tokenizer does internally.
 (Contributed by Ammar Askar in :issue:`33899`.)
+
+Notable changes in Python 3.7.2
+===============================
+
+In 3.7.2, :mod:`venv` on Windows no longer copies the original binaries, but
+creates redirector scripts named ``python.exe`` and ``pythonw.exe`` instead.
+This resolves a long standing issue where all virtual environments would have
+to be upgraded or recreated with each Python update. However, note that this
+release will still require recreation of virtual environments in order to get
+the new scripts.