Fix compatibility with setuptools >= 66

The Python world, including the `setuptools` package, has migrated to
the versioning scheme defined in PEP 440. Unfortunately, the versioning
of Jenkins plugins is less strict than that. As a consequence,
`pkg_resources.parse_version()` now rejects versions as invalid.

Fix `PluginVersion` by salvaging the implementation of the old
`LegacyVersion` class, which used to be part of the `packaging` library
prior to version 22.0. The code is licensed under a 2-clause BSD
licence.

For compatibility with older Python versions, remove type annotations
from the copied code.

Change-Id: Iaa057dcd81620fed861cb11bed534ff7f9ab3f32
Signed-off-by: Christoph Erhardt <ce+ubuntuone@sicherha.de>

jenkins/plugins.py

@@ -42,8 +42,6 @@
 import operator
 import re
 
-import pkg_resources
-
 
 class Plugin(dict):
     '''Dictionary object containing plugin metadata.'''
@@ -76,15 +74,13 @@ class PluginVersion(str):
         '''Parse plugin version and store it for comparison.'''
 
         self._version = version
-        self.parsed_version = pkg_resources.parse_version(
-            self.__convert_version(version))
+        self._key = _legacy_cmpkey(self.__convert_version(version))
 
     def __convert_version(self, version):
         return self._VERSION_RE.sub(r'\g<1>.preview', str(version))
 
     def __compare(self, op, version):
-        return op(self.parsed_version, pkg_resources.parse_version(
-            self.__convert_version(version)))
+        return op(self._key, PluginVersion(version)._key)
 
     def __le__(self, version):
         return self.__compare(operator.le, version)
@@ -109,3 +105,92 @@ class PluginVersion(str):
 
     def __repr__(self):
         return str(self._version)
+
+
+###############################################################################
+"""
+The Python world has migrated to the versioning scheme defined in PEP 440, but
+the versioning of Jenkins plugins is less strict than that. The code below was
+salvaged from the implementation of the `LegacyVersion` class, which used to be
+part of the `packaging` library prior to version 22.0.
+
+It is licensed as follows.
+
+Copyright (c) Donald Stufft and individual contributors.
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    1. Redistributions of source code must retain the above copyright notice,
+       this list of conditions and the following disclaimer.
+
+    2. Redistributions in binary form must reproduce the above copyright
+       notice, this list of conditions and the following disclaimer in the
+       documentation and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+"""
+
+_legacy_version_component_re = re.compile(r"(\d+ | [a-z]+ | \.| -)", re.VERBOSE)
+
+_legacy_version_replacement_map = {
+    "pre": "c",
+    "preview": "c",
+    "-": "final-",
+    "rc": "c",
+    "dev": "@",
+}
+
+
+def _parse_version_parts(s):
+    for part in _legacy_version_component_re.split(s):
+        part = _legacy_version_replacement_map.get(part, part)
+
+        if not part or part == ".":
+            continue
+
+        if part[:1] in "0123456789":
+            # pad for numeric comparison
+            yield part.zfill(8)
+        else:
+            yield "*" + part
+
+    # ensure that alpha/beta/candidate are before final
+    yield "*final"
+
+
+def _legacy_cmpkey(version):
+
+    # We hardcode an epoch of -1 here. A PEP 440 version can only have a epoch
+    # greater than or equal to 0. This will effectively put the LegacyVersion,
+    # which uses the defacto standard originally implemented by setuptools,
+    # as before all PEP 440 versions.
+    epoch = -1
+
+    # This scheme is taken from pkg_resources.parse_version setuptools prior to
+    # it's adoption of the packaging library.
+    parts = []
+    for part in _parse_version_parts(version.lower()):
+        if part.startswith("*"):
+            # remove "-" before a prerelease tag
+            if part < "*final":
+                while parts and parts[-1] == "*final-":
+                    parts.pop()
+
+            # remove trailing zeros from each series of numeric parts
+            while parts and parts[-1] == "00000000":
+                parts.pop()
+
+        parts.append(part)
+
+    return epoch, tuple(parts)

requirements.txt

@@ -1,5 +1,3 @@
-# Setuptools removed support for PEP 440 non-conforming versions
-setuptools<66
 six>=1.3.0
 pbr>=0.8.2
 multi_key_dict