completion for 'args.' or '(args).' was causing error, so I escaped the asterisk.
a:v -> escape(a:v) in GetRubyVarType for *args
There is an existing issue that tries to deal with this problem in a different way, issue #98. I'm not very familiar with the completion script, which is why I kept postponing a decision on it. Your fix seems safer, since it looks like it fixes the particular error, avoiding any side effects. Hopefully :).
Thanks for your work. Merging in.