And still no test case. :p

| iris% cat test_jpeg.pike | int main() | { | string s = Stdio.read_bytes("sugar.jpg"); | object i = Image.JPEG.decode(s); | string out = Image.JPEG.encode(i); | write("%O\n",out[..5]); | return 0; | } | iris% pike test_jpeg.pike | "\377\330\377\340\0\20"