Problem:

$ zsh -c 'while getopts x: opt; do echo "$opt"; done' dummy -x
zsh:1: argument expected after -x option
:

Expected output: the ':' at the end should be a '?'. The opt variable 
should only be set to ':' in "quiet" mode, i.e. if the option string 
starts with a ':' (so in this case would be ':x:').

Ref.: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/getopts.html
(the two bullet points following "If an option-argument is missing:").

The attached patch fixes this to match POSIX and the behaviour of every 
other shell.

- Martijn

-- 
modernish -- harness the shell
https://github.com/modernish/modernish