python: return urls with also dash -> underscore

lib/spack/spack/build_systems/python.py

@@ -354,9 +354,21 @@ def homepage(cls) -> Optional[str]:  # type: ignore[override]
         return None
 
     @lang.classproperty
-    def url(cls) -> Optional[str]:
+    def urls(cls) -> Optional[List[str]]:
         if cls.pypi:
-            return f"https://files.pythonhosted.org/packages/source/{cls.pypi[0]}/{cls.pypi}"
+            urls = [
+                f"https://files.pythonhosted.org/packages/source/{cls.pypi[0]}/{cls.pypi}"
+            ]
+            assert cls.pypi.count("/") == 1, "PyPI class attribute must include a single slash"
+            name, file = cls.pypi.split("/")
+            name_dash_count = name.count("-")
+            if name_dash_count > 0:
+                # replace all but last dash with underscores for pypi.org listing changes
+                pypi = "/".join([name, file.replace("-", "_", name_dash_count)])
+                urls.append(
+                    f"https://files.pythonhosted.org/packages/source/{pypi[0]}/{pypi}"
+                )
+            return urls
         return None
 
     @lang.classproperty