fix error return from wait builtin in a subshell when there are no children of this shell

lib/readline/doc/readline.3

@@ -1057,7 +1057,7 @@ leaving the current line at the top of the screen.
 Clear the screen,
 then redraw the current line,
 leaving the current line at the top of the screen.
-With an argument, refresh the current line without clearing the
+With a numeric argument, refresh the current line without clearing the
 screen.
 .TP
 .B redraw\-current\-line

lib/readline/doc/rluser.texi

@@ -1388,6 +1388,8 @@ leaving the current line at the top of the screen.
 Clear the screen,
 then redraw the current line,
 leaving the current line at the top of the screen.
+If given a numeric argument, this refreshes the current line
+without clearing the screen.
 
 @item redraw-current-line ()
 Refresh the current line.  By default, this is unbound.

lib/sh/zgetline.c

@@ -43,7 +43,7 @@ typedef ssize_t breadfunc_t (int, char *, size_t);
 typedef ssize_t creadfunc_t (int, char *);
 
 /* Initial memory allocation for automatic growing buffer in zreadlinec */
-#define GET_LINE_INITIAL_ALLOCATION 16
+#define GET_LINE_INITIAL_ALLOCATION 64
 
 /* Derived from GNU libc's getline.
    The behavior is almost the same as getline. See man getline.