This patch was discussed here:

http://www.zsh.org/cgi-bin/mla/redirect?usernumber=6812

Executive summary:

 1. some people have complained that running zsh's configure in the
    background hangs when checking for broken tcsetpgrp().

 2. some people have complained that if they run zsh's configure a
    some magic build script that does not have a controlling tty, then
    zsh is built incorrectly (tcsetpgrp() is then assumed broken).

 - this patch takes care of #1 by blocking SIGTTOU during the duration
   of the "checking for broken tcsetpgrp" test.

 - this patch takes care of #2 by adding a new ./configure option
   --with-tcsetpgrp, which behaves this way:

     * under normal circumstances (running with a ctty), this option
       is not needed.

     * ./configure will abort and report "Try running configure with
       --with-tcsetpgrp or --without-tcsetpgrp" if this option is
       needed (running WITHOUT a ctty).

     * when --with-tcsetpgrp is specified, the "checking for broken
       tcsetpgrp" test is skipped.

     * when --without-tcsetpgrp is specified, the "checking for broken
       tcsetpgrp" test is skipped and BROKEN_TCSETPGRP is AC_DEFINED.

Shall we consider this for inclusion?

Phil.

Patch against latest CVS sources: