Fix(bzlmod): Windows Python Interpreter symlink issues

When using Windows you cannot run the symlink directly.

Because of how symlinks work in Windows we need to use the path
realink.
Unlike Linux and OSX we cannot execute the Python symlink directly.
Windows throws an error "-1073741515", when we execute the symlink
directory.  This error means that the Python binary cannot find dlls.
This is because the symlink that we create is not in the same folder
as the dlls.

This commit introduces code that resolves the actual location of the
interpreter using the path realink when we are running bzlmod and
Windows.

python/pip_install/pip_repository.bzl

@@ -15,9 +15,11 @@
 ""
 
 load("//python:repositories.bzl", "get_interpreter_dirname", "is_standalone_interpreter")
+load("//python:versions.bzl", "WINDOWS_NAME")
 load("//python/pip_install:repositories.bzl", "all_requirements")
 load("//python/pip_install:requirements_parser.bzl", parse_requirements = "parse")
 load("//python/pip_install/private:srcs.bzl", "PIP_INSTALL_PY_SRCS")
+load("//python/private:toolchains_repo.bzl", "get_host_os_arch")
 
 CPPFLAGS = "CPPFLAGS"
 
@@ -72,8 +74,14 @@ def _resolve_python_interpreter(rctx):
     python_interpreter = _get_python_interpreter_attr(rctx)
 
     if rctx.attr.python_interpreter_target != None:
-        target = rctx.attr.python_interpreter_target
-        python_interpreter = rctx.path(target)
+        python_interpreter = rctx.path(rctx.attr.python_interpreter_target)
+        # If we have @@ we have bzlmod so we need to hand Windows differently.
+        if str(Label("//:unused")).startswith("@@"):
+            (os, _) = get_host_os_arch(rctx)
+            # If we have Windows the symlink will not work directly and we need
+            # to resolve the realpath.
+            if os == WINDOWS_NAME:
+                python_interpreter = python_interpreter.realpath
     elif "/" not in python_interpreter:
         found_python_interpreter = rctx.which(python_interpreter)
         if not found_python_interpreter:
@@ -670,7 +678,6 @@ py_binary(
 
 def _whl_library_impl(rctx):
     python_interpreter = _resolve_python_interpreter(rctx)
-
     args = [
         python_interpreter,
         "-m",
@@ -699,7 +706,7 @@ def _whl_library_impl(rctx):
     )
 
     if result.return_code:
-        fail("whl_library %s failed: %s (%s)" % (rctx.attr.name, result.stdout, result.stderr))
+        fail("whl_library %s failed: %s (%s) error code: '%s'" % (rctx.attr.name, result.stdout, result.stderr, result.return_code))
 
     return