[svn-r10699] Improve the check for a valid stdin.

No reviewer.

src/pm/hydra/tools/demux/demux.c

@@ -235,19 +235,7 @@ HYD_status HYDT_dmxi_stdin_valid(int *out)
     }
 #endif /* SIGTTIN and HAVE_ISATTY */
 
-    /* FIXME: The below read() check for STDIN validity is somehow
-     * interfering in the case where the application is run in the
-     * background, but expects some STDIN. The correct behavior is to
-     * close the STDIN socket for the application in that
-     * case. However, this seems to hang. I'm still investigating this
-     * case. In the meanwhile, I have commented out this check. PLEASE
-     * DO NOT DELETE. All other cases dealing with STDIN seem to be
-     * working correctly. */
-#if 0
     ret = read(STDIN_FILENO, NULL, 0);
-#else
-    ret = 0;
-#endif
     if (ret < 0 && errno == EINTR && got_sigttin)
         *out = 0;
     else