Fish-shell: eval $argv unparses the arguments

• [x] Have you checked if problem occurs with fish 2.4.0?
• [x] Tried fish without third-party customizations (check sh -c 'env HOME=$(mktemp -d) fish')?

fish version installed (fish --version): 2.4.0

OS/terminal used: OSX 10.12.2 (16C67) / iTerm2 Build 3.0.13

Let's say I have a simple script that just outputs its arguments. It could look something like this:

#!/usr/bin/env ruby
p ARGV

and its execution looks like this:

> ./myscript.rb foo 'hello world'
["foo", "hello world"]

Notice how "hello world" is grouped as one argument vs "hello" and "world" being separate arguments.

Now, I want to write a fish function that lets me execute any arbitrary fish command (including aliases) with some ENV vars set up.

This is my first attempt of such function

function debug
  set -xg DEBUG 1
  eval $argv
  set -e DEBUG
end

Here's what happens when I run my script from above through this function:

> debug ./myscript.rb foo 'hello world'
["foo", "hello", "world"]

Notice that single "hello world" argument turned into "hello" and "world", which is not what I wanted.

I've also tried the following approach:

env DEBUG=1 fish -c "$argv"

Which produced the same result.

Is there any way to make the function's $argv preserve "hello world" grouping? What am I missing?