Revert "use importlib.resources to acquire doctest resources"

This reverts commit 9b850e7.

Author: graingert

Lib/doctest.py

@@ -102,8 +102,7 @@ def _test():
 import sys
 import traceback
 import unittest
-import importlib.resources
-from io import StringIO
+from io import StringIO, IncrementalNewlineDecoder
 from collections import namedtuple
 import _colorize  # Used in doctests
 from _colorize import ANSIColors, can_colorize
@@ -236,31 +235,25 @@ def _normalize_module(module, depth=2):
     else:
         raise TypeError("Expected a module, string, or None")
 
+def _newline_convert(data):
+    # The IO module provides a handy decoder for universal newline conversion
+    return IncrementalNewlineDecoder(None, True).decode(data, True)
+
 def _load_testfile(filename, package, module_relative, encoding):
     if module_relative:
         package = _normalize_module(package, 3)
         filename = _module_relative_path(package, filename)
-        try:
-            loader = package.__loader__
-        except AttributeError:
-            pass
-        else:
-            if loader is not None:
-                return (
-                    importlib.resources.read_text(package, filename, encoding=encoding),
-                    filename,
-                )
-
-        try:
-            package.__spec__.loader
-        except AttributeError:
-            pass
-        else:
-            return (
-                importlib.resources.read_text(package, filename, encoding=encoding),
-                filename,
-            )
-
+        if (loader := getattr(package, '__loader__', None)) is None:
+            try:
+                loader = package.__spec__.loader
+            except AttributeError:
+                pass
+        if hasattr(loader, 'get_data'):
+            file_contents = loader.get_data(filename)
+            file_contents = file_contents.decode(encoding)
+            # get_data() opens files as 'rb', so one must do the equivalent
+            # conversion as universal newlines would do.
+            return _newline_convert(file_contents), filename
     with open(filename, encoding=encoding) as f:
         return f.read(), filename