warning about closing an already closed file descriptor

[Kamil Dudka <kdudka@xxxxxxxxxx>]

zsh prints a warning if an already closed file descriptor is to be closed.  
While this is technically correct, the other shells I tried (ksh and bash)
do not print any such warning:

$ bash -c '(true <&-) <&-'
$ ksh -c '(true <&-) <&-'
$ zsh -c '(true <&-) <&-'
zsh:1: failed to close file descriptor 0: bad file descriptor

The warning was introduced by the following commit:
http://sourceforge.net/p/zsh/code/ci/45913f43

... and it causes problems when porting legacy scripts to a newer version
of zsh.  Is there any way to suppress the warning?

If not, how can one achieve compatibility with other shells (including
older versions of zsh)?

Kamil