I apologize if I sounded patronizing. If you would oblige me a minute longer, could you edit the execute() method of the VcsUpgrader class on line 449 of Package Control.py to be the following?
def execute(self, args, dir):
startupinfo = None
if os.name == 'nt':
startupinfo = subprocess.STARTUPINFO()
startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
print args
print dir
proc = subprocess.Popen(args, stdin=subprocess.PIPE,
stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
startupinfo=startupinfo, cwd=dir)
return proc.stdout.read().replace('\r\n', '\n').rstrip(' \n\r')
When you save the file, it should automatically try to execute the upgrader, and it should print what it is trying to execute and the directory it is trying to execute in.