ksh reading file via command substitution is broken in RHEL 6.5

Issue

Reading a file via command substitution does not work in anymore if stdin or stdout or stderr are closed. The output differs from the same for ksh in RHEL 6.4.

With ksh-20120801-10.el6_5.3.x86_64:

$ ksh -c 'echo .$(</proc/sys/kernel/osrelease).'
.2.6.32-431.5.1.el6.x86_64.
$ ksh -c 'echo .$(</proc/sys/kernel/osrelease).' <&-
..
$ ksh -c 'echo .$(</proc/sys/kernel/osrelease). >&2' >&-
..
$ ksh -c 'echo .$(</proc/sys/kernel/osrelease).' 2>&-
..

With ksh-20100621-19.el6_4.4.x86_64:

$ ksh -c 'echo .$(</proc/sys/kernel/osrelease).'
.2.6.32-431.5.1.el6.x86_64.
$ ksh -c 'echo .$(</proc/sys/kernel/osrelease).' <&-
.2.6.32-431.3.1.el6.x86_64.
$ ksh -c 'echo .$(</proc/sys/kernel/osrelease). >&2' >&-
.2.6.32-431.3.1.el6.x86_64.
$ ksh -c 'echo .$(</proc/sys/kernel/osrelease).' 2>&-
.2.6.32-431.3.1.el6.x86_64.