avoid useless call to groebner_basis

Author: rprebet

src/algorithms/dimension.jl

@@ -19,7 +19,9 @@ julia> dimension(I)
 """
 function dimension(I::Ideal{T}) where T <: MPolyRingElem
 
-    gb = get(I.gb, 0, groebner_basis(I, complete_reduction = true))
+    gb = get!(I.gb, 0) do
+        groebner_basis(I, complete_reduction = true)
+    end
     R = parent(first(gb))
 
     res = Set([trues(ngens(R))])