I got into the same problem on my MAC (High Sierra) and deleting the .DS_Store did not help. But I noticed that if I rename the manifest.safe file to manifest.xml everything works well. So the quick fix I am using is copying the file programmatically from manifest.safe to manifest.xml before trying to open it and this works well:
shutil.copyfile(pathdir + “manifest.safe”, pathdir + “manifest.xml”)
product = snappy.ProductIO.readProduct(pathdir + “manifest.xml”)