12364 mdb trips assertion related to autowrap

@@ -22,11 +22,11 @@
  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
 
 /*
- * Copyright 2017 Joyent, Inc.
+ * Copyright 2020 Joyent, Inc.
  */
 
 /*
  * Support for ::set dcmd.  The +/-o option processing code is provided in a
  * stand-alone function so it can be used by the command-line option processing

@@ -273,11 +273,11 @@
         /*
          * The ::set output implicitly relies on "autowrap" being enabled, so
          * we enable it for the duration of the command.
          */
         oflags = mdb.m_flags;
-        mdb.m_flags |= MDB_FL_AUTOWRAP;
+        mdb_iob_set_autowrap(mdb.m_out);
 
         mdb_printf("follow_exec_mode=");
         switch (mdb.m_execmode) {
         case MDB_EM_ASK:
                 mdb_printf("ask");