--- ruby-2.5.5/ext/readline/readline.c.old	2017-09-30 08:35:23.000000000 +0000
+++ ruby-2.5.5/ext/readline/readline.c	2019-09-09 06:12:00.300098741 +0000
@@ -572,6 +572,9 @@
             rb_syserr_fail(save_errno, "fdopen");
         }
         rl_instream = readline_rl_instream = f;
+#ifdef HAVE_EDITLINE_READLINE_H
+        rl_initialize();
+#endif
         readline_instream = input;
     }
     return input;
@@ -608,6 +611,9 @@
             rb_syserr_fail(save_errno, "fdopen");
         }
         rl_outstream = readline_rl_outstream = f;
+#ifdef HAVE_EDITLINE_READLINE_H
+        rl_initialize();
+#endif
         readline_outstream = output;
     }
     return output;