The following patch solves the problem.
*** readline/readline.c~1 Fri Jan 12 18:24:20 1996
--- readline/readline.c Sun May 5 18:09:28 1996
*************** rl_read_init_file (filename)
*** 5765,5772 ****
--- 5765,5778 ----
i = read (file, buffer, finfo.st_size);
close (file);
+ #ifdef __MSDOS__
+ if (i < 0)
+ return (errno);
+ finfo.st_size = i;
+ #else
if (i != finfo.st_size)
return (errno);
+ #endif
/* Loop over the lines in the file. Lines that start with `#' are
comments; all other lines are commands for readline initialization. *