Description of problem:
ksh $? not set correctly

Version-Release number of selected component (if applicable):
$ /bin/ksh --version
  version         sh (AT&T Research) 93t 2008-11-04

How reproducible:
Always

Steps to Reproduce:
$ cat ksh-test
#!/bin/ksh

findprocesspid()
{
    pid="`cat /dev/null`"

    if [ "${pid}" = "" ]; then
        false
    else
        echo "${pid}"
        true
    fi
}

findprocesspid
echo $?

pid=`findprocesspid `
echo $? $pid  

Actual results:
$ /bin/ksh ksh-test
1
0

Expected results:
$ /mnt/ubuntu/bin/ksh93 --version
  version         sh (AT&T Research) 93s+ 2008-01-31
$ /mnt/ubuntu/bin/ksh93 ksh-test
1
1


Additional info:
Official build of ksh version 93t works as expected.