POSIX requires ${##""} to be parsed as ${parameter#word} with parameter
of # and word of "", which results in the output of $# with the shortest
prefix of the empty string removed (aka ${#}).  But current zsh.git
rejects this:

$ ./Src/zsh -c 'set a b; echo ${##""}'
zsh:1: bad substitution

Worse, this is a regression:

$ zsh -c 'set a b; echo ${##""}'
2
$ rpm -q zsh
zsh-4.3.10-5.fc14.x86_64

-- 
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org