Regression reading exr images

[Carl Eugen Hoyos]

​http://thread.gmane.org/gmane.comp.video.ffmpeg.user/57302

The second output file is black, regression since 9f6d48d6

$ cp fate-suite/exr/rgba_slice_raw.exr test1.exr
$ cp fate-suite/exr/rgba_slice_raw.exr test2.exr

$ ffmpeg -threads 1 -i test%1d.exr out%1d.dpx
ffmpeg version N-72695-g440fa77 Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 4.7 (SUSE Linux)
  configuration: --enable-gpl
  libavutil      54. 27.100 / 54. 27.100
  libavcodec     56. 41.101 / 56. 41.101
  libavformat    56. 34.100 / 56. 34.100
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 16.101 /  5. 16.101
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  2.100 /  1.  2.100
  libpostproc    53.  3.100 / 53.  3.100
Input #0, image2, from 'test%1d.exr':
  Duration: 00:00:00.08, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: exr, rgba64le, 587x675 [SAR 1:1 DAR 587:675], 25 tbr, 25 tbn, 25 tbc
Output #0, image2, to 'out%1d.dpx':
  Metadata:
    encoder         : Lavf56.34.100
    Stream #0:0: Video: dpx, rgba64le, 587x675 [SAR 1:1 DAR 587:675], q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc
    Metadata:
      encoder         : Lavc56.41.101 dpx
Stream mapping:
  Stream #0:0 -> #0:0 (exr (native) -> dpx (native))
Press [q] to stop, [?] for help
[exr @ 0x371d860] Found more than one compression attribute.
frame=    2 fps=0.0 q=-1.0 Lsize=N/A time=00:00:00.08 bitrate=N/A
video:6194kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

[Carl Eugen Hoyos]

Apparently a duplicate of ticket #4597 - fixed in a03b69478b7f1c0c31e53acb0cf392917c0f967a