Remove handle_py3_kw_only_args

- Drop handle_py3_kw_only_args() which is no longer needed, and was mislabeled.
  The root issue was my confusion between keyword-only arguments (*) and
  position-only arguments (/), the first being added in early 3.x and the later
  being a 3.8+ feature.  So the feature I wanted was already there, nice!

ksconf/builder/__init__.py

@@ -8,7 +8,6 @@
 from subprocess import Popen
 from typing import Callable, List, TextIO
 
-from ksconf.compat import handle_py3_kw_only_args
 from ksconf.consts import EXIT_CODE_INTERNAL_ERROR, is_debug
 
 QUIET = -1
@@ -76,8 +75,7 @@ def _log(self, message, verbosity=0):
             self._output.write(message)
             self._output.write("\n")
 
-    def run(self, executable, *args, **kw_only):
-        # PY38 signature:  run(self, executable, /, *args, cwd=None)
+    def run(self, executable, *args, cwd=None):
         """ Execute an OS-level command regarding the build process.
         The process will run withing the working directory of the build folder.
 
@@ -86,7 +84,6 @@ def run(self, executable, *args, **kw_only):
         :param str cwd:  Optional kw arg to change the working directory.  This
                          defaults to the build folder.
         """
-        (cwd,) = handle_py3_kw_only_args(kw_only, ("cwd", None))
         # XXX: Update the external pip call to detach stdout / stderr if self.is_quiet
         args = [executable] + [str(s) for s in args]
         cwd = cwd or str(self.build_path)

ksconf/compat.py

@@ -38,48 +38,6 @@
     from functools import lru_cache
     cache = lru_cache(maxsize=None)
 
-
-def handle_py3_kw_only_args(kw, *default_args):
-    """ Fake support for Python 3.8+ style keyword-only style arguments, or ``*`` arg syntax.
-
-    Example Python 3.8+ syntax:
-
-    ..  code-block:: py
-
-        def f(arg, *args, a=True, b=False):
-            ...
-
-    Example Python 3.7 (and earlier) syntax with this helper function:
-
-    ..  code-block:: py
-
-        def f(arg, *args, **kw_only):
-            a, b = handle_py3_kw_only_args(kw_only, ("a", True), ("b", False))
-            ...
-
-    :param dict kw: keyword arguments provided to the calling function. Be aware
-                    that this dict will be empty after this function is done.
-    :param tuple default_args: pairs of keyword argument to the caller function
-                               in argument (arg_name, default_value) order.
-    :raises TypeError: if ``kw`` contains any keys not defined in ``args``
-                       This mirrors Python's native behavior when an unexpected
-                       argument is passed to a function.
-    """
-    out = []
-    for arg_name, arg_default in default_args:
-        try:
-            out.append(kw.pop(arg_name))
-        except KeyError:
-            out.append(arg_default)
-    if kw:
-        import inspect
-        caller = inspect.currentframe().f_back.f_code.co_name
-        # Should all unexpected args be reported?  feels like this good enough
-        raise TypeError("{} got an unexpected keyword argument '{}'"
-                        .format(caller, list(kw)[0]))
-    return out
-
-
 del sys
 
 __all__ = [
@@ -88,5 +46,4 @@ def f(arg, *args, **kw_only):
     "Set",
     "Tuple",
     "cache",
-    "handle_py3_kw_only_args",
 ]