diff --git a/xarray/coding/variables.py b/xarray/coding/variables.py
index 3b7be898ccf..eff08c74500 100644
--- a/xarray/coding/variables.py
+++ b/xarray/coding/variables.py
@@ -164,10 +164,8 @@ def _check_fill_values(attrs, name, dtype):
     Issue SerializationWarning if appropriate.
     """
     raw_fill_dict = {}
-    [
+    for attr in ("missing_value", "_FillValue"):
         pop_to(attrs, raw_fill_dict, attr, name=name)
-        for attr in ("missing_value", "_FillValue")
-    ]
     encoded_fill_values = set()
     for k in list(raw_fill_dict):
         v = raw_fill_dict[k]
@@ -376,11 +374,9 @@ def decode(self, variable: Variable, name: T_Name = None):
 
         dims, data, attrs, encoding = unpack_for_decoding(variable)
 
-        # Even if _Unsigned is use, retain on-disk _FillValue
-        [
+        # Even if _Unsigned is used, retain on-disk _FillValue
+        for attr, value in raw_fill_dict.items():
             safe_setitem(encoding, attr, value, name=name)
-            for attr, value in raw_fill_dict.items()
-        ]
 
         if "_Unsigned" in attrs:
             unsigned = pop_to(attrs, encoding, "_Unsigned")
diff --git a/xarray/tests/test_dask.py b/xarray/tests/test_dask.py
index ccb832ee522..9024f2ae677 100644
--- a/xarray/tests/test_dask.py
+++ b/xarray/tests/test_dask.py
@@ -1129,7 +1129,8 @@ def test_unify_chunks(map_ds):
 def test_unify_chunks_shallow_copy(obj, transform):
     obj = transform(obj)
     unified = obj.unify_chunks()
-    assert_identical(obj, unified) and obj is not obj.unify_chunks()
+    assert_identical(obj, unified)
+    # assert obj is not unified
 
 
 @pytest.mark.parametrize("obj", [make_da()])