I need an alternative to the shutil module in particular shutil.copyfile.
It is a little known bug with py2exe that makes the entire shutil module useless.
Using os.system() will be problematic for many reasons; for example, when you have spaces or Unicode in the file names.   It will also be more opaque relative to exceptions/failures.
If this is on windows, using win32file.CopyFile() is probably the best approach, since that will yield the correct file attributes, dates, permissions, etc. relative to the original file (that is, it will be more similar to the results you'd get by using Explorer to copy the file).
Alternative to shutil.copyfile