-b -M does not fill in max bitrate field
$ oggenc -b 128 -M 130 -o test2.ogg file.wav
$ hex test2.ogg | head -10
0x00000000: 4f 67 67 53 00 02 00 00 - 00 00 00 00 00 00 2a 0d OggS..........*.
0x00000010: 72 54 00 00 00 00 2d 01 - 74 8a 01 1e 01 76 6f 72 rT....-.t....vor
0x00000020: 62 69 73 00 00 00 00 02 - 44 ac 00 00 ff ff ff ff bis.....D.......
0x00000030: 1f f4 01 00 ff ff ff ff - b8 01 4f 67 67 53 00 00 ..........OggS..
The min/max bitrate fields are still "ff ff ff ff" (-1). The nominal bitrate
field is correctly set to "1f f4 01 00" (128031).