"av_interleaved_write_frame(): Broken pipe" when make mosaic stream from 2 other streams

[Konstantin]

Summary of the bug:
How to reproduce:

ffmpeg -i http://195.154.182.204:8083/camera3/h264 -i http://195.154.182.204:8083/camera2/h264 -filter_complex "nullsrc=size=640x240 [bg]; [0:v] setpts=PTS-STARTPTS, scale=320x240 [v0];[1:v] setpts=PTS-STARTPTS, scale=320x240 [v1]; [bg][v0] overlay=shortest=1 [bg+v0]; [bg+v0][v1] overlay=shortest=1:x=320" -map "[out]" -codec:v libx264 http://82.138.54.213:8090/feed.ffm
ffmpeg version N-71320-gc4b2017 Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 4.4.7 (GCC) 20120313 (Red Hat 4.4.7-11)
  configuration: --enable-nonfree --enable-gpl --enable-libfdk_aac --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264
  libavutil      54. 22.100 / 54. 22.100
  libavcodec     56. 34.100 / 56. 34.100
  libavformat    56. 29.100 / 56. 29.100
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 13.101 /  5. 13.101
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
Input #0, flv, from 'http://195.154.182.204:8083/camera3/h264':
  Duration: 00:00:00.00, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: h264 (High), yuvj420p(pc), 640x480, 200 kb/s, 15.17 fps, 12.08 tbr, 1k tbn, 30 tbc
    Stream #0:1: Audio: aac (LC), 8000 Hz, mono, fltp, 64 kb/s
Input #1, flv, from 'http://195.154.182.204:8083/camera2/h264':
  Duration: 00:00:00.00, start: 0.000000, bitrate: N/A
    Stream #1:0: Video: h264 (High), yuvj420p(pc), 640x480, 200 kb/s, 15.17 fps, 15 tbr, 1k tbn, 30 tbc
    Stream #1:1: Audio: aac (LC), 8000 Hz, mono, fltp, 64 kb/s
[swscaler @ 0x36150c0] deprecated pixel format used, make sure you did set range correctly
[swscaler @ 0x361ed00] deprecated pixel format used, make sure you did set range correctly
[swscaler @ 0x372c820] deprecated pixel format used, make sure you did set range correctly
[swscaler @ 0x3737e60] deprecated pixel format used, make sure you did set range correctly
[libx264 @ 0x3a056a0] using SAR=1/1
[libx264 @ 0x3a056a0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.1 Cache64
[libx264 @ 0x3a056a0] profile High, level 2.1
Output #0, ffm, to 'http://82.138.54.213:8090/feed.ffm':
  Metadata:
    creation_time   : now
    encoder         : Lavf56.29.100
    Stream #0:0: Video: h264 (libx264), yuv420p, 640x240 [SAR 1:1 DAR 8:3], q=-1--1, 25 fps, 1000k tbn, 25 tbc
    Metadata:
      encoder         : Lavc56.34.100 libx264
    Stream #0:1: Video: flv1 (flv), yuv420p, 640x480, q=1-5, 200 kb/s, 12.08 fps, 1000k tbn, 30 tbc
    Metadata:
      encoder         : Lavc56.34.100 flv
    Stream #0:2: Video: flv1 (flv), yuv420p, 640x480, q=1-5, 100 kb/s, 12.08 fps, 1000k tbn, 30 tbc
    Metadata:
      encoder         : Lavc56.34.100 flv
Stream mapping:
  Stream #0:0 (h264) -> setpts (graph 0)
  Stream #1:0 (h264) -> setpts (graph 0)
  overlay (graph 0) -> Stream #0:0 (libx264)
  Stream #0:0 -> #0:1 (h264 (native) -> flv1 (flv))
  Stream #0:0 -> #0:2 (h264 (native) -> flv1 (flv))
Press [q] to stop, [?] for help
[flv @ 0x363cfe0] Thread message queue blocking; consider raising the thread_queue_size option (current value: 8)
[flv @ 0x370b7e0] Thread message queue blocking; consider raising the thread_queue_size option (current value: 8)
av_interleaved_write_frame(): Broken pipeize=       4kB time=00:00:01.46 bitrate=  22.3kbits/s dup=52 drop=0
frame=   42 fps= 39 q=28.0 Lq=31.0 q=31.0 size=      72kB time=00:00:01.73 bitrate= 340.3kbits/s dup=62 drop=0
video:401kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
[libx264 @ 0x3a056a0] frame I:1     Avg QP:20.05  size: 33093
[libx264 @ 0x3a056a0] frame P:11    Avg QP:23.53  size:  2854
[libx264 @ 0x3a056a0] frame B:30    Avg QP:29.52  size:   173
[libx264 @ 0x3a056a0] consecutive B-frames:  2.4%  4.8%  7.1% 85.7%
[libx264 @ 0x3a056a0] mb I  I16..4:  8.3% 21.0% 70.7%
[libx264 @ 0x3a056a0] mb P  I16..4:  0.1%  0.0%  0.0%  P16..4: 14.2%  9.4% 12.3%  0.0%  0.0%    skip:64.0%
[libx264 @ 0x3a056a0] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8: 13.2%  1.6%  0.6%  direct: 0.5%  skip:84.1%  L0:33.3% L1:61.5% BI: 5.3%
[libx264 @ 0x3a056a0] 8x8 transform intra:21.9% inter:45.3%
[libx264 @ 0x3a056a0] coded y,uvDC,uvAC intra: 91.2% 83.3% 58.0% inter: 5.1% 2.5% 0.2%
[libx264 @ 0x3a056a0] i16 v,h,dc,p:  7% 44% 11% 37%
[libx264 @ 0x3a056a0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu:  9% 44% 18%  4%  2%  2%  5%  3% 13%
[libx264 @ 0x3a056a0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 24% 29% 11%  5%  5%  5%  7%  5%  9%
[libx264 @ 0x3a056a0] i8c dc,h,v,p: 47% 28% 20%  6%
[libx264 @ 0x3a056a0] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0x3a056a0] ref P L0: 74.1%  8.8% 13.8%  3.3%
[libx264 @ 0x3a056a0] ref B L0: 87.4% 11.3%  1.3%
[libx264 @ 0x3a056a0] ref B L1: 91.5%  8.5%
[libx264 @ 0x3a056a0] kb/s:331.72
Conversion failed!.