require importlib_metadata

The stdlib importlib.metadata returns duplicate distributions
(and entry points) in some circumstances for all python versions
up to and including 3.11.

python/importlib_metadata#410 (comment)

The above issue can create duplicate asdf extensions.

This fixes issue #1254

fix changelog typo

CHANGES.rst

@@ -1,3 +1,10 @@
+2.14.3 (unreleased)
+-------------------
+
+The ASDF Standard is at v1.6.0
+
+- Use importlib_metadata for all python versions [#1260]
+
 2.14.2 (2022-12-05)
 -------------------
 

asdf/entry_points.py

@@ -1,10 +1,9 @@
-import sys
 import warnings
 
-if sys.version_info < (3, 10):
-    from importlib_metadata import entry_points
-else:
-    from importlib.metadata import entry_points
+# The standard library importlib.metadata returns duplicate entrypoints
+# for all python versions up to and including 3.11
+# https://github.com/python/importlib_metadata/issues/410#issuecomment-1304258228
+from importlib_metadata import entry_points
 
 from .exceptions import AsdfWarning
 from .extension import ExtensionProxy

asdf/tests/test_entry_points.py

@@ -1,12 +1,9 @@
-import sys
-
+# The standard library importlib.metadata returns duplicate entrypoints
+# for all python versions up to and including 3.11
+# https://github.com/python/importlib_metadata/issues/410#issuecomment-1304258228
+import importlib_metadata as metadata
 import pytest
 
-if sys.version_info < (3, 10):
-    import importlib_metadata as metadata
-else:
-    import importlib.metadata as metadata
-
 from asdf import entry_points
 from asdf._version import version as asdf_package_version
 from asdf.exceptions import AsdfWarning

asdf/util.py

@@ -4,23 +4,21 @@
 import math
 import re
 import struct
-import sys
 import types
 from functools import lru_cache
 from importlib import metadata
 from urllib.request import pathname2url
 
 import numpy as np
+
+# The standard library importlib.metadata returns duplicate entrypoints
+# for all python versions up to and including 3.11
+# https://github.com/python/importlib_metadata/issues/410#issuecomment-1304258228
+from importlib_metadata import packages_distributions
 from packaging.version import Version
 
 from . import constants
 
-if sys.version_info < (3, 10):
-    from importlib_metadata import packages_distributions
-else:
-    from importlib.metadata import packages_distributions
-
-
 # We're importing our own copy of urllib.parse because
 # we need to patch it to support asdf:// URIs, but it'd
 # be irresponsible to do this for all users of a

docs/conf.py

@@ -1,13 +1,12 @@
 from pathlib import Path
 
 import tomli
-from sphinx_asdf.conf import *  # noqa: F403
-
-try:
-    from importlib.metadata import distribution
-except ImportError:
-    from importlib_metadata import distribution
 
+# The standard library importlib.metadata returns duplicate entrypoints
+# for all python versions up to and including 3.11
+# https://github.com/python/importlib_metadata/issues/410#issuecomment-1304258228
+from importlib_metadata import distribution
+from sphinx_asdf.conf import *  # noqa: F403
 
 # Get configuration information from `pyproject.toml`
 with open(Path(__file__).parent.parent / "pyproject.toml", "rb") as configuration_file:

pyproject.toml

@@ -18,7 +18,7 @@ dependencies = [
     'asdf-transform-schemas >=0.2.2',
     'asdf-unit-schemas >= 0.1.0',
     'importlib_resources >=3; python_version <"3.9"',
-    'importlib-metadata >=3; python_version <"3.10"',
+    'importlib-metadata >=4.11.4',
     'jmespath >=0.6.2',
     'jsonschema >=4.0.1',
     'numpy >=1.18',