review fixes

Author: vitek

src/pluggy/_hooks.py

@@ -338,7 +338,7 @@ def set_specification(
         spec_opts: "_HookSpecOpts",
     ) -> None:
         if self.spec is not None:
-            raise RuntimeError(
+            raise ValueError(
                 f"Hook {self.spec.name!r} is already registered "
                 f"within namespace {self.spec.namespace}"
             )

testing/test_hookcaller.py

@@ -419,5 +419,9 @@ def conflict(self) -> None:
             pass
 
     pm.add_hookspecs(Api1)
-    with pytest.raises(RuntimeError):
+    with pytest.raises(ValueError) as exc:
         pm.add_hookspecs(Api2)
+    assert str(exc.value) == (
+        "Hook 'conflict' is already registered within namespace "
+        "<class 'test_hookcaller.test_hook_conflict.<locals>.Api1'>"
+    )