Some short MPG files give "Invalid data found when processing input"

[Ridley Combs]

Summary of the bug:
Some small MPG files give "invalid data" errors early-on. I'm attempting to gather more sample files, and details on what produces them. QuickTime has no problem playing them.
How to reproduce:

$ ffmpeg -loglevel debug -i MOV27379.MPG 
ffmpeg version N-65478-g6985ef7 Copyright (c) 2000-2014 the FFmpeg developers
  built on Aug  9 2014 22:54:35 with Apple LLVM version 6.0 (clang-600.0.34.4) (based on LLVM 3.5svn)
  configuration: --extra-cflags='-march=native' --enable-optimizations --enable-debug --enable-libx265 --enable-gpl --enable-libopus --enable-version3 --enable-nonfree --enable-postproc --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-gnutls --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --prefix=/usr/local --enable-static --enable-shared --enable-avresample --enable-vda --enable-opencl --enable-libzvbi --cc=clang
  libavutil      54.  0.100 / 54.  0.100
  libavcodec     56.  0.100 / 56.  0.100
  libavformat    56.  0.100 / 56.  0.100
  libavdevice    56.  0.100 / 56.  0.100
  libavfilter     5.  0.100 /  5.  0.100
  libavresample   2.  0.  0 /  2.  0.  0
  libswscale      3.  0.100 /  3.  0.100
  libswresample   1.  0.100 /  1.  0.100
  libpostproc    53.  0.100 / 53.  0.100
Splitting the commandline.
Reading option '-loglevel' ... matched as option 'loglevel' (set logging level) with argument 'debug'.
Reading option '-i' ... matched as input file with argument 'MOV27379.MPG'.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option loglevel (set logging level) with argument debug.
Successfully parsed a group of options.
Parsing a group of options: input file MOV27379.MPG.
Successfully parsed a group of options.
Opening an input file: MOV27379.MPG.
[AVIOContext @ 0x7f84b040fd80] Statistics: 30269 bytes read, 0 seeks
MOV27379.MPG: Invalid data found when processing input

The one sample I have so far:
​http://puu.sh/aT6mn/dab3a98d31.MPG

[Ridley Combs]

Additional sample files are available here: ​https://www.dropbox.com/sh/6987vzlqjhsmg1e/AACrfRFMas8PTZri9QYyPHYja
Apparently these files come from a SONY DSC-W170, and the issue manifests with files sized at 40kB or smaller.

[Carl Eugen Hoyos]

mp3 and program stream detection both return the same score for the sample.

[Carl Eugen Hoyos]

Regression since c4674a47
Related to 5afdb3e6 / 64bde805

[Michael Niedermayer]

Fixed in 5109ce2017c15202275b33bce58ec9d88044eeb5