problems with a subshell in .profile

[Nils]

I use a shared .profile for bash and ksh93, I have a ksh93 specific
section which I want to separate through the following construct:

if ( test -n "${.sh.version}" ) 2>/dev/null; then
    echo "ksh"
fi

bash just hangs while it works in POSIX shell and ksh93. A bash script
with above contents also works as expected.
Why is this?