diff -r 7d1211168863 -r a2e191a937a9 contrib/packaging/hgpackaging/py2exe.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/contrib/packaging/hgpackaging/py2exe.py	Thu Mar 07 15:43:54 2019 -0800
@@ -0,0 +1,125 @@
+# py2exe.py - Functionality for performing py2exe builds.
+#
+# Copyright 2019 Gregory Szorc <gregory.szorc@gmail.com>
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+
+# no-check-code because Python 3 native.
+
+import os
+import pathlib
+import subprocess
+
+from .downloads import (
+    download_entry,
+)
+from .util import (
+    extract_tar_to_directory,
+    extract_zip_to_directory,
+    python_exe_info,
+)
+
+
+def build_py2exe(source_dir: pathlib.Path, build_dir: pathlib.Path,
+                 python_exe: pathlib.Path, build_name: str,
+                 venv_requirements_txt: pathlib.Path):
+    """Build Mercurial with py2exe.
+
+    Build files will be placed in ``build_dir``.
+
+    py2exe's setup.py doesn't use setuptools. It doesn't have modern logic
+    for finding the Python 2.7 toolchain. So, we require the environment
+    to already be configured with an active toolchain.
+    """
+    if 'VCINSTALLDIR' not in os.environ:
+        raise Exception('not running from a Visual C++ build environment; '
+                        'execute the "Visual C++ <version> Command Prompt" '
+                        'application shortcut or a vcsvarsall.bat file')
+
+    # Identity x86/x64 and validate the environment matches the Python
+    # architecture.
+    vc_x64 = r'\x64' in os.environ['LIB']
+
+    py_info = python_exe_info(python_exe)
+
+    if vc_x64:
+        if py_info['arch'] != '64bit':
+            raise Exception('architecture mismatch: Visual C++ environment '
+                            'is configured for 64-bit but Python is 32-bit')
+    else:
+        if py_info['arch'] != '32bit':
+            raise Exception('architecture mismatch: Visual C++ environment '
+                            'is configured for 32-bit but Python is 64-bit')
+
+    if py_info['py3']:
+        raise Exception('Only Python 2 is currently supported')
+
+    build_dir.mkdir(exist_ok=True)
+
+    gettext_pkg, gettext_entry = download_entry('gettext', build_dir)
+    gettext_dep_pkg = download_entry('gettext-dep', build_dir)[0]
+    virtualenv_pkg, virtualenv_entry = download_entry('virtualenv', build_dir)
+    py2exe_pkg, py2exe_entry = download_entry('py2exe', build_dir)
+
+    venv_path = build_dir / ('venv-%s-%s' % (build_name,
+                                             'x64' if vc_x64 else 'x86'))
+
+    gettext_root = build_dir / (
+        'gettext-win-%s' % gettext_entry['version'])
+
+    if not gettext_root.exists():
+        extract_zip_to_directory(gettext_pkg, gettext_root)
+        extract_zip_to_directory(gettext_dep_pkg, gettext_root)
+
+    # This assumes Python 2. We don't need virtualenv on Python 3.
+    virtualenv_src_path = build_dir / (
+        'virtualenv-%s' % virtualenv_entry['version'])
+    virtualenv_py = virtualenv_src_path / 'virtualenv.py'
+
+    if not virtualenv_src_path.exists():
+        extract_tar_to_directory(virtualenv_pkg, build_dir)
+
+    py2exe_source_path = build_dir / ('py2exe-%s' % py2exe_entry['version'])
+
+    if not py2exe_source_path.exists():
+        extract_zip_to_directory(py2exe_pkg, build_dir)
+
+    if not venv_path.exists():
+        print('creating virtualenv with dependencies')
+        subprocess.run(
+            [str(python_exe), str(virtualenv_py), str(venv_path)],
+            check=True)
+
+    venv_python = venv_path / 'Scripts' / 'python.exe'
+    venv_pip = venv_path / 'Scripts' / 'pip.exe'
+
+    subprocess.run([str(venv_pip), 'install', '-r', str(venv_requirements_txt)],
+                   check=True)
+
+    # Force distutils to use VC++ settings from environment, which was
+    # validated above.
+    env = dict(os.environ)
+    env['DISTUTILS_USE_SDK'] = '1'
+    env['MSSdk'] = '1'
+
+    py2exe_py_path = venv_path / 'Lib' / 'site-packages' / 'py2exe'
+    if not py2exe_py_path.exists():
+        print('building py2exe')
+        subprocess.run([str(venv_python), 'setup.py', 'install'],
+                       cwd=py2exe_source_path,
+                       env=env,
+                       check=True)
+
+    # Register location of msgfmt and other binaries.
+    env['PATH'] = '%s%s%s' % (
+        env['PATH'], os.pathsep, str(gettext_root / 'bin'))
+
+    print('building Mercurial')
+    subprocess.run(
+        [str(venv_python), 'setup.py',
+         'py2exe', '-b', '3' if vc_x64 else '2',
+         'build_doc', '--html'],
+        cwd=str(source_dir),
+        env=env,
+        check=True)