MAINT: ignore exclude_applied on legacy plugins (#844)

imageio/core/legacy_plugin_wrapper.py

@@ -294,8 +294,8 @@ def metadata(self, index=None, exclude_applied: bool = True):
             The index of the ndimage to read. If the index is out of bounds a
             ``ValueError`` is raised. If ``None``, global metadata is returned.
         exclude_applied : bool
-            If True (default), do not report metadata fields that the plugin
-            would apply/consume while reading the image.
+            This parameter exists for compatibility and has no effect. Legacy
+            plugins always report all metadata they find.
 
         Returns
         -------
@@ -305,11 +305,6 @@ def metadata(self, index=None, exclude_applied: bool = True):
 
         """
 
-        if exclude_applied:
-            raise ValueError(
-                "Legacy plugins don't support excluding applied metadata fields."
-            )
-
         if index is None:
             index = _legacy_default_index(self._format)
 

tests/test_legacy_plugin_wrapper.py

@@ -24,13 +24,6 @@ def test_exception_message_bytes():
         assert "<bytes>" in str(e)
 
 
-def test_exclude_applied(test_images):
-    with pytest.raises(ValueError):
-        iio.v3.immeta(
-            test_images / "chelsea.png", exclude_applied=True, plugin="PNG-PIL"
-        )
-
-
 def test_ellipsis_index(test_images):
     img = iio.v3.imread(test_images / "chelsea.png", plugin="PNG-FI", index=...)
     assert img.shape == (1, 300, 451, 3)