<unset> removes struct entries with inheritance again

gwinc/__init__.py

@@ -132,7 +132,11 @@ def load_budget(name_or_path, freq=None, bname=None):
 
                 inherit_budget = load_budget(inherit_ifo, freq=freq, bname=bname)
                 pre_ifo = inherit_budget.ifo
-                pre_ifo.update(ifo, overwrite_atoms=False)
+                pre_ifo.update(
+                    ifo,
+                    overwrite_atoms=False,
+                    clear_test=lambda v: isinstance(v, str) and v == '<unset>'
+                )
                 inherit_budget.update(ifo=pre_ifo)
                 return inherit_budget
             else:

test/inherit/Aplus_mod3.yaml

++inherit: 'Aplus'
+
+# test that unset removes struct entries
+Optics:
+    Quadrature: <unset>
\ No newline at end of file

test/inherit/test_inherit.py

@@ -36,6 +36,14 @@ def test_inherit_load(pprint, tpath_join, fpath_join):
         ])
     )
 
+    fpath3 = fpath_join('Aplus_mod3.yaml')
+    B_inherit3 = load_budget(fpath3)
+    pprint(B_inherit3.ifo.diff(B_orig.ifo))
+    assert(
+        B_inherit3.ifo.diff(B_orig.ifo)
+        == [('Optics.Quadrature.dc', None, 1.5707963)]
+    )
+
 
 @pytest.mark.fast
 @pytest.mark.logic