redirections preceded by a word with builtins inconsistent

[adonis papaderos]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64' -DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-pc-linux-gnu' -DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL -DHAVE_CONFIG_H   -I.  -I../. -I.././include -I.././lib  -D_FORTIFY_SOURCE=2 -g -O2 -fstack-protector-strong -Wformat -Werror=format-security -Wall
uname output: Linux venus 4.4.0-22-generic #40-Ubuntu SMP Thu May 12 22:03:46 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 4.3
Patch Level: 42
Release Status: release

Description:
    When using redirections preceded by a word on builtins
        'i.e. : {varname}<&1'
        the redirection persists to the current shell.
        Later using {varname}<&- does not close fd.


Repeat-By:
    ls -l /proc/self/fd
    : {varname}<&1
    ls -l /proc/self/fd
    {varname}<&-
    : ls -l /proc/self/fd