ksh regression wrong return code from a function

Issue

• Under some circumstances, one gets an incorrect return code from a function.
• Refer Test script:

#!/bin/ksh

foo() {
  z=shift
  print -r $z | read
  return 1
}

bar() {
  z=shift
  print -r $z | read
  cat /dev/null
  return 1
}

out=$(foo "foo")
res=$?
echo Res is: $res

out=$(bar "bar")
res=$?
echo Res is: $res


[root@localhost ~]# cat /etc/redhat-release 
Red Hat Enterprise Linux Server release 6.4 (Santiago)
[root@localhost doug]# rpm -qa ksh
ksh-20100621-19.el6_4.4.x86_64
[root@localhost doug]# ksh --version
  version         sh (AT&T Research) 93t+ 2010-06-21
[root@localhost doug]# vi testscript.sh
[root@localhost doug]# chmod 755 testscript.sh 
[root@localhost doug]# su - doug
[doug@localhost ~]$ ./testscript.sh 
Res is: 1
Res is: 1
[doug@localhost ~]$ exit
logout
[root@localhost doug]# 

[root@localhost doug]# ls
ksh-20120801-10.el6_5.6.x86_64.rpm  testscript.sh
[root@localhost doug]# rpm -q ksh
ksh-20100621-19.el6_4.4.x86_64
[root@localhost doug]# rpm -e ksh-20100621-19.el6_4.4       
[root@localhost doug]# rpm -ivh ksh-20120801-10.el6_5.6.x86_64.rpm 
Preparing...                ########################################### [100%]
   1:ksh                    ########################################### [100%]
[root@localhost doug]# 
[root@localhost doug]# ksh --version
  version         sh (AT&T Research) 93u+ 2012-08-01
[root@localhost doug]# 
[root@localhost doug]# su - doug
[doug@localhost ~]$ ./testscript.sh 
Res is: 0                       <============wrong value
Res is: 1
[doug@localhost ~]$