Upgraded graft img is always overridden

[Newbiespud 44]

I'm surprised no one's run into this yet, but not even the example mods have upgraded grafts, so:

Making modded grafts goes well enough until you make an upgraded form, a _plus form. If you specify an "img =" field, even if you're absolutely perfect with the filename, all you'll get is the dreaded Pink Square. Why?

I blame Content.AddGraft. Specifically this first bit here.

local function AddGraft( id, graft_def )
    assert(id, "NO ID FOR GRAFT")

    graft_def.id = id

    local basic_id = graft_def.base_id or id:match( "(.*)_plus.*$" )
    if basic_id then
        UpgradeGraft( id, graft_def, basic_id )
    end

    -- Generate conventional icon paths for non-upgraded cards. 
    if graft_def.img == nil or basic_id then
        local path
        if graft_def.type == GRAFT_TYPE.MUTATOR then
            path = string.format( "icons/mutators/%s.tex", id:lower() )
        elseif graft_def.type == GRAFT_TYPE.PERK then
            path = string.format( "icons/perks/perk_%s.tex", id:lower() )
        else
            path = string.format( "icons/items/graft_%s.tex", graft_def.icon_override or id:lower() )
        end
        graft_def.img = engine.asset.Texture( path, true )
        graft_def.img_path = graft_def.img and path
        if graft_def.img:IsDefault() then
            graft_def.img = global_images.default
        end
    end

Even if graft_def.img is not nil (as in it's specified by the file), if the graft has a basic_id (which it will by virtue of being a _plus), then the function will override the def's img by looking in the data/icons/items folder for a texture that likely won't exist.

If you're reusing existing textures (which I am for the most part), you can get around this by specifying an icon_override field instead of an img field. But for any modder trying to add a file from outisde data.zip? In its current form, I'm pretty sure they're out of luck right now.

[rooks 240]

I've fixed this in the mainline currently, pending an update.  Grafts (including upgraded ones) can specify an img explicitly to use:
 

example_graft =
{
	name = "Example Graft",
	img = "icons/items/graft_whatever.tex",
	...