Failures on Fedora-i686, branch master

[Pedro Alves]

> new FAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 1: break at break_fn: 1 (the program is no longer running)
> new FAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 1: break at break_fn: 2 (the program is no longer running)
> new FAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 1: break at break_fn: 3 (the program is no longer running)
> new FAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 1: detach (the program is no longer running)

Bonkers, I thought these would be completely fixed
with 20ba1ce66d31b9dd16ed8c648f46ce32aa3a03e0.

What's now odd is that this is failing already on iteration 1, with:

 (gdb) kill
 The program is not being run.
 (gdb) file /home/gdb-buildbot/fedora-x86-64-2/fedora-i686/build/gdb/testsuite/outputs/gdb.threads/attach-many-short-lived-threads/attach-many-short-lived-threads
 Reading symbols from /home/gdb-buildbot/fedora-x86-64-2/fedora-i686/build/gdb/testsuite/outputs/gdb.threads/attach-many-short-lived-threads/attach-many-short-lived-threads...done.
 (gdb) attach 5159
 Attaching to program: /home/gdb-buildbot/fedora-x86-64-2/fedora-i686/build/gdb/testsuite/outputs/gdb.threads/attach-many-short-lived-threads/attach-many-short-lived-threads, process 5159
 warning: process 5159 is a zombie - the process has already terminated
 ptrace: Operation not permitted.
 (gdb) PASS: gdb.threads/attach-many-short-lived-threads.exp: iter 1: attach
 info threads
 No threads.

The test should be fixed to detect that, but, OTOH, the test program
sleeps for 180 seconds before exiting:

  /* Long enough for all the attach/detach sequences done by the .exp
     file.  */
  sleep (180);
  return 0;
}

so how come the _first_ attach already fails like that?

Thanks,
Pedro Alves