FFMPEG x264 bug

ffmpeg -loglevel debug -y -probesize 5000000 -i test090.mov -c:a pcm_s16le -ar 48000 -vn test090_audio.wav
ffmpeg version 1.1.git Copyright (c) 2000-2013 the FFmpeg developers
  built on Mar  4 2013 11:40:27 with Apple clang version 4.1 (tags/Apple/clang-421.11.66) (based on LLVM 3.1svn)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-nonfree --enable-hardcoded-tables --enable-avresample --cc=cc --host-cflags= --host-ldflags= --enable-libx264 --enable-libfaac --enable-libmp3lame --enable-libxvid --enable-libfreetype --enable-ffplay
  libavutil      52. 17.103 / 52. 17.103
  libavcodec     54. 92.100 / 54. 92.100
  libavformat    54. 63.102 / 54. 63.102
  libavdevice    54.  3.103 / 54.  3.103
  libavfilter     3. 41.100 /  3. 41.100
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
Splitting the commandline.
Reading option '-loglevel' ... matched as option 'loglevel' (set libav* logging level) with argument 'debug'.
Reading option '-y' ... matched as option 'y' (overwrite output files) with argument '1'.
Reading option '-probesize' ... matched as AVOption 'probesize' with argument '5000000'.
Reading option '-i' ... matched as input file with argument 'test090.mov'.
Reading option '-c:a' ... matched as option 'c' (codec name) with argument 'pcm_s16le'.
Reading option '-ar' ... matched as option 'ar' (set audio sampling rate (in Hz)) with argument '48000'.
Reading option '-vn' ... matched as option 'vn' (disable video) with argument '1'.
Reading option 'test090_audio.wav' ... matched as output file.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option loglevel (set libav* logging level) with argument debug.
Applying option y (overwrite output files) with argument 1.
Successfully parsed a group of options.
Parsing a group of options: input file test090.mov.
Successfully parsed a group of options.
Opening an input file: test090.mov.
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fc46b00f200] Format mov,mp4,m4a,3gp,3g2,mj2 probed with size=2048 and score=100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fc46b00f200] ISO: File Type Major Brand: qt
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fc46b00f200] File position before avformat_find_stream_info() is 69918
[h264 @ 0x7fc46b029c00] Using externally provided dimensions
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fc46b00f200] All info found
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fc46b00f200] File position after avformat_find_stream_info() is 360883
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test090.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 537199360
    compatible_brands: qt
    creation_time   : 2013-02-19 19:49:54
  Duration: 00:03:00.04, start: 0.000000, bitrate: 8340 kb/s
    Stream #0:0(eng), 46, 1/48000: Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, stereo, s16, 1536 kb/s
    Metadata:
      creation_time   : 2013-02-19 19:49:54
      handler_name    : Apple Alias Data Handler
    Stream #0:1(eng), 1, 1/24: Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1280x720, 1/48, 6801 kb/s, 24 fps, 24 tbr, 24 tbn, 48 tbc
    Metadata:
      creation_time   : 2013-02-19 19:49:54
      handler_name    : Apple Alias Data Handler
Successfully opened the file.
Parsing a group of options: output file test090_audio.wav.
Applying option c:a (codec name) with argument pcm_s16le.
Applying option ar (set audio sampling rate (in Hz)) with argument 48000.
Applying option vn (disable video) with argument 1.
Successfully parsed a group of options.
Opening an output file: test090_audio.wav.
Successfully opened the file.
[abuffer @ 0x7fc46ac14980] Setting entry with key 'time_base' to value '1/48000'
[abuffer @ 0x7fc46ac14980] Setting entry with key 'sample_rate' to value '48000'
[abuffer @ 0x7fc46ac14980] Setting entry with key 'sample_fmt' to value 's16'
[abuffer @ 0x7fc46ac14980] Setting entry with key 'channel_layout' to value '0x3'
[graph 0 input from stream 0:0 @ 0x7fc46ac14a40] tb:1/48000 samplefmt:s16 samplerate:48000 chlayout:0x3
[aformat @ 0x7fc46ac14f40] Setting entry with key 'sample_fmts' to value 's16'
[aformat @ 0x7fc46ac14f40] Setting entry with key 'sample_rates' to value '48000'
Output #0, wav, to 'test090_audio.wav':
  Metadata:
    major_brand     : qt
    minor_version   : 537199360
    compatible_brands: qt
    ISFT            : Lavf54.63.102
    Stream #0:0(eng), 0, 1/48000: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, stereo, s16, 1536 kb/s
    Metadata:
      creation_time   : 2013-02-19 19:49:54
      handler_name    : Apple Alias Data Handler
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le -> pcm_s16le)
Press [q] to stop, [?] for help
[output stream 0:0 @ 0x7fc46ac14ca0] EOF on sink link output stream 0:0:default.
No more output streams to write to, finishing.
size=   33758kB time=00:03:00.04 bitrate=1536.0kbits/s
video:0kB audio:33758kB subtitle:0 global headers:0kB muxing overhead 0.000231%
Statistics: 35553280 bytes read, 360 seeks