report weight if s=t in yen_k_shortest_simple_paths

Author: kappybar

src/sage/graphs/path_enumeration.pyx

@@ -734,19 +734,29 @@ def yen_k_shortest_simple_paths(self, source, target, weight_function=None,
          [1, 6, 9, 10, 5],
          [1, 6, 9, 3, 4, 5],
          [1, 6, 9, 11, 10, 5]]
+
+    When s = t and report_edge=True and report_weight=True (issue 40247)::
+
+        sage: g = DiGraph([(1, 2)])
+        sage: list(yen_k_shortest_simple_paths(g, 1, 1, report_edges=True, report_weight=True))
+        [(0, [])]
     """
     if source not in self:
         raise ValueError("vertex '{}' is not in the graph".format(source))
     if target not in self:
         raise ValueError("vertex '{}' is not in the graph".format(target))
 
     if source == target:
-        if report_edges:
-            yield []
-        elif report_weight:
-            yield (0, [source])
+        if report_weight:
+            if report_edges:
+                yield (0, [])
+            else:
+                yield (0, [source])
         else:
-            yield [source]
+            if report_edges:
+                yield []
+            else:
+                yield [source]
         return
 
     if self.has_loops() or self.allows_multiple_edges():