Deploying Node.JS app to Heroku - Caching issues?

I'm currently trying to push my app to Heroku. I already been able to deploy it a few times, but now I've updated mongoose from ">= 3.5.0" to ">= 3.6.0rc0" in my packages.json file. However, version 3.6 requires mpath and mpromise.

When the slug compilation begins, it uses a cached version of mongoose or something, as my when my application launches, I get "Error: Cannot find module 'mpath'".

I trying to setup a custom buildpack Git that would stop the caching, I just commented out the cache stuff in bin/compile, available here: https://github.com/jValdron/heroku-buildpack-nodejs

Here is an output of the push: http://pastebin.com/L3Yqy2NR

Also, when I removed some dependencies from package.json, if I login with 'heroku run bash', I can see that those removed dependencies in node_modules. I already tried to remove the node_modules folder and do another 'git push', that didn't work either. And those removed deps are still in node_modules.

Anyone have an idea on how to fix this?

EDIT:

Here is my package.json file:

{
    "name": "souply-api",
    "version": "0.1.0",
    "author": "Jason Valdron <jason.valdron@orangesprocket.com>",
    "description": "Main gears that runs the Soup.ly application",
    "dependencies": {
        "bcrypt": ">= 0.7.3",
        "express": ">= 3.0.5",
        "extend": ">= 1.1.3",
        "imagemagick": ">= 0.1.3",
        "jade": ">= 0.27.7",
        "knox": ">= 0.4.6", 
        "less": ">= 1.3.1",
        "less-middleware": ">= 0.1.9",
        "moment": ">= 1.7.2",
        "mongoose": ">= 3.6.0rc0", 
        "mongoose-types": ">= 1.0.3",
        "node-native-zip": ">= 1.1.0",
        "nodemailer": ">= 0.3.37",
        "oauth2orize": ">= 0.1.0",
        "passport": ">= 0.1.15",
        "passport-local": ">= 0.1.6",
        "passport-google": ">= 0.2.0",
        "passport-facebook": ">= 0.1.4",
        "passport-twitter": ">= 0.1.4",
        "passport-http": ">= 0.2.1",
        "passport-http-bearer": ">= 0.2.0",
        "passport-oauth2-client-password": ">= 0.1.0",
        "poor-form": ">= 1.1.3",
        "request": ">= 2.12.0",
        "socket.io": ">= 0.9.13"
    },
    "engines": {
        "node": "0.8.x",
        "npm": "1.1.x"
    }
}

Mongoose is set as 3.6.0rc, as previously said. Mpath is a dependencies in Mongoose's package.json file. If I look at my local mongoose package.json file, I can see this:

"dependencies": {
    "hooks": "0.2.1"
  , "mongodb": "1.2.11"
  , "ms": "0.1.0"
  , "sliced": "0.0.3"
  , "muri": "0.3.0"
  , "mpromise": "0.2.0"
  , "mpath": "0.1.1"
}

Also, if I login with heroku run bash, and navigate to node_modules/mongoose/node_modules I see that mpath and mpromise is not there.