Windows gVim, shell starts in HOME instead of working directory

Question

I've recently have gotten sick of constantly switching between Windows and Linux and installed gVim and MSYS2 on Windows 7. After a couple hours of searching I have a .vimrc that makes !command, make, etc. that use the shell and utilities that come with MSYS2 instead of cmd.exe (located below). However, whenever I run a shell commands the shell starts in my home directory instead of vim's current working directory. I know this is the fault of the the shell flag --login, but if I remove it the shell complains that it cant find any commands: /usr/bin/bash: ls: command not found. I presume this is because PATH isn't set.

Is it possible to keep bash from starting in home? Or, more possibly, how do I modify gVim's PATH to inherit from MSYS's PATH?

if has('win32') || has('win64')
    set runtimepath=$HOME/.vim,$VIM/vimfiles,$VIMRUNTIME,$VIM/vimfiles/after,$HOME/.vim/after
    set shell=C:\msys64\usr\bin\bash
    set shellcmdflags=--login\ -c
    set shellslash
endif