fix #4552

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/smt/diff_logic.h

@@ -511,6 +511,7 @@ public:
     // Return false if the resultant graph has a negative cycle. The negative
     // cycle can be extracted using traverse_neg_cycle.
     // The method assumes the graph is feasible before the invocation.
+
     bool enable_edge(edge_id id) {
         edge& e = m_edges[id];
         SASSERT(is_feasible_dbg());