Simplify combing SpecifierSet.prereleases (#1073)

Author: notatallshaw

src/packaging/specifiers.py

@@ -922,11 +922,10 @@ def __and__(self, other: SpecifierSet | str) -> SpecifierSet:
         specifier = SpecifierSet()
         specifier._specs = frozenset(self._specs | other._specs)
 
-        if self._prereleases is None and other._prereleases is not None:
+        # Combine prerelease settings: use common or non-None value
+        if self._prereleases is None or self._prereleases == other._prereleases:
             specifier._prereleases = other._prereleases
-        elif (
-            self._prereleases is not None and other._prereleases is None
-        ) or self._prereleases == other._prereleases:
+        elif other._prereleases is None:
             specifier._prereleases = self._prereleases
         else:
             raise ValueError(