Fix retrocompatbility of numversion

Closes pylint-dev#4420

pylint/__pkginfo__.py

@@ -1,5 +1,6 @@
 # Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 # For details: https://github.com/PyCQA/pylint/blob/master/LICENSE
+from typing import Tuple
 
 from pkg_resources import DistributionNotFound, get_distribution
 
@@ -8,5 +9,27 @@
 except DistributionNotFound:
     __version__ = "2.8.2+"
 
-# Kept for compatibility reason, see https://github.com/PyCQA/pylint/issues/4399
-numversion = tuple(__version__.split("."))
+
+def get_numversion_from_version(v: str) -> Tuple:
+    """Kept for compatibility reason
+
+    See https://github.com/PyCQA/pylint/issues/4399
+    https://github.com/PyCQA/pylint/issues/4420,
+    """
+    v = v.replace("pylint-", "")
+    version = []
+    for n in v.split(".")[0:3]:
+        try:
+            version.append(int(n))
+        except ValueError:
+            num = ""
+            for c in n:
+                if c.isdigit():
+                    num += c
+                else:
+                    break
+            version.append(int(num))
+    return tuple(version)
+
+
+numversion = get_numversion_from_version(__version__)

tests/test_numversion.py

@@ -0,0 +1,23 @@
+# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+# For details: https://github.com/PyCQA/pylint/blob/master/LICENSE
+
+import pytest
+
+from pylint.__pkginfo__ import get_numversion_from_version
+
+
+@pytest.mark.parametrize(
+    "version,expected_numversion",
+    [
+        ["2.8.1", (2, 8, 1)],
+        ["2.8.2+", (2, 8, 2)],
+        ["3.0.0a0", (3, 0, 0)],
+        ["3.0.0b1", (3, 0, 0)],
+        ["3.0.0rc1", (3, 0, 0)],
+        ["3.0.0dev-234324234234f23abc4", (3, 0, 0)],
+        ["pylint-2.4.7", (2, 4, 7)],
+        ["2.8.3.dev3+g28c093c2.d20210428", (2, 8, 3)],
+    ],
+)
+def test_numversion(version, expected_numversion):
+    assert get_numversion_from_version(version) == expected_numversion