Retire commands `setup.py symlink`, `setup.py unsymlink` (#14327)

Apparently introduced in  #4473 (over 10 years ago), undocumented.

setup.py

@@ -74,10 +74,6 b' from setupbase import ('
     check_package_data_first,
     find_data_files,
     git_prebuild,
-    install_symlinked,
-    install_lib_symlink,
-    install_scripts_for_symlink,
-    unsymlink,
 )
 
 #-------------------------------------------------------------------------------
@@ -135,10 +131,6 b" setup_args['cmdclass'] = {"
     'build_py': \
             check_package_data_first(git_prebuild('IPython')),
     'sdist' : git_prebuild('IPython', sdist),
-    'symlink': install_symlinked,
-    'install_lib_symlink': install_lib_symlink,
-    'install_scripts_sym': install_scripts_for_symlink,
-    'unsymlink': unsymlink,
 }
 
 setup_args["entry_points"] = {

setupbase.py

@@ -181,74 +181,10 b' def find_entry_points():'
     major_suffix = str(sys.version_info[0])
     return [e % "" for e in ep] + [e % major_suffix for e in ep]
 
-
-class install_lib_symlink(Command):
-    user_options = [
-        ('install-dir=', 'd', "directory to install to"),
-        ]
-
-    def initialize_options(self):
-        self.install_dir = None
-
-    def finalize_options(self):
-        self.set_undefined_options('symlink',
-                                   ('install_lib', 'install_dir'),
-                                  )
-
-    def run(self):
-        if sys.platform == 'win32':
-            raise Exception("This doesn't work on Windows.")
-        pkg = os.path.join(os.getcwd(), 'IPython')
-        dest = os.path.join(self.install_dir, 'IPython')
-        if os.path.islink(dest):
-            print('removing existing symlink at %s' % dest)
-            os.unlink(dest)
-        print('symlinking %s -> %s' % (pkg, dest))
-        os.symlink(pkg, dest)
-
-class unsymlink(install):
-    def run(self):
-        dest = os.path.join(self.install_lib, 'IPython')
-        if os.path.islink(dest):
-            print('removing symlink at %s' % dest)
-            os.unlink(dest)
-        else:
-            print('No symlink exists at %s' % dest)
-
-class install_symlinked(install):
-    def run(self):
-        if sys.platform == 'win32':
-            raise Exception("This doesn't work on Windows.")
-
-        # Run all sub-commands (at least those that need to be run)
-        for cmd_name in self.get_sub_commands():
-            self.run_command(cmd_name)
-
-    # 'sub_commands': a list of commands this command might have to run to
-    # get its work done.  See cmd.py for more info.
-    sub_commands = [('install_lib_symlink', lambda self:True),
-                    ('install_scripts_sym', lambda self:True),
-                   ]
-
-class install_scripts_for_symlink(install_scripts):
-    """Redefined to get options from 'symlink' instead of 'install'.
-
-    I love distutils almost as much as I love setuptools.
-    """
-    def finalize_options(self):
-        self.set_undefined_options('build', ('build_scripts', 'build_dir'))
-        self.set_undefined_options('symlink',
-                                   ('install_scripts', 'install_dir'),
-                                   ('force', 'force'),
-                                   ('skip_build', 'skip_build'),
-                                  )
-
-
 #---------------------------------------------------------------------------
 # VCS related
 #---------------------------------------------------------------------------
 
-
 def git_prebuild(pkg_dir, build_cmd=build_py):
     """Return extended build or sdist command class for recording commit