This is a backport from bash-4.4-rc1 and might help to avoid to run
onto a not existing child pointer, bnc#971410.

---
 jobs.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- jobs.c
+++ jobs.c	2016-04-01 08:32:53.898981856 +0000
@@ -2564,12 +2564,12 @@ itrace("wait_for: blocking wait for %d r
      of the last child in the pipeline is the significant one.  If the command
      or job was terminated by a signal, note that value also. */
   termination_state = (job != NO_JOB) ? job_exit_status (job)
-				      : process_exit_status (child->status);
+				      : (child ? process_exit_status (child->status) : EXECUTION_SUCCESS);
   last_command_exit_signal = (job != NO_JOB) ? job_exit_signal (job)
-					     : process_exit_signal (child->status);
+					     : (child ? process_exit_signal (child->status) : 0);
 
   /* XXX */
-  if ((job != NO_JOB && JOBSTATE (job) == JSTOPPED) || WIFSTOPPED (child->status))
+  if ((job != NO_JOB && JOBSTATE (job) == JSTOPPED) || (child && WIFSTOPPED (child->status)))
     termination_state = 128 + WSTOPSIG (child->status);
 
   if (job == NO_JOB || IS_JOBCONTROL (job))