sendme: Turn log warning into debug

When sending the stream level SENDME, it is possible the cirucit was marked
for close or any other failures that can occur. These events can occur
naturally.

Fixes #40142

Signed-off-by: David Goulet <dgoulet@torproject.org>

changes/ticket40142

@@ -0,0 +1,3 @@
+  o Minor bugfixes (logging, flow control):
+    - Turn a SENDME failure log warning into a debug. It can actually happen
+      naturally. Fixes bug 40142; bugfix on 0.4.1.1-alpha.

src/core/or/sendme.c

@@ -398,8 +398,8 @@ sendme_connection_edge_consider_sending(edge_connection_t *conn)
     conn->deliver_window += STREAMWINDOW_INCREMENT;
     if (connection_edge_send_command(conn, RELAY_COMMAND_SENDME,
                                      NULL, 0) < 0) {
-      log_warn(LD_BUG, "connection_edge_send_command failed while sending "
-                       "a SENDME. Circuit probably closed, skipping.");
+      log_debug(LD_CIRC, "connection_edge_send_command failed while sending "
+                         "a SENDME. Circuit probably closed, skipping.");
       goto end; /* The circuit's closed, don't continue */
     }
   }