fix previous commit.

don't use S_ISDIR.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@8811 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

io.c

@@ -379,10 +379,9 @@ wsplit_p(OpenFile *fptr)
     if (!(fptr->mode & FMODE_WSPLIT_INITIALIZED)) {
         struct stat buf;
         if (fstat(fptr->fd, &buf) == 0 &&
-            !(S_ISREG(buf.st_mode) ||
-              S_ISDIR(buf.st_mode))
+            !S_ISREG(buf.st_mode)
 #if defined(HAVE_FCNTL) && defined(F_GETFL) && defined(O_NONBLOCK)
-            && (r = fcntl(fileno(f), F_GETFL)) != -1 &&
+            && (r = fcntl(fptr->fd, F_GETFL)) != -1 &&
             !(r & O_NONBLOCK)
 #endif
             ) {