#2 export in parentheses subshell

[rcrnstn]

If we run the following, we get what is expected:

$ Z=1
$ ( export Z=2; printenv Z )
2

However, when we have already exported the variable to the environment it doesn't get updated

$ export Z=1
$ ( export Z=2; printenv Z )
1

I haven't managed to get the original zsh 3.0.8 to compile on any *nix so I can't say if the bug is in there, I do know however that it is not present in zsh 4.3.10 (on Ubuntu 10.04)
Seems likely this is WinZsh specific

$ echo $ZSH_VERSION
3.0.8deb14_NT_0.78.1