[FFmpeg-user] http inside concat demuxer

[rslovers at yandex.com]

   I tried:
           ffmpeg -user-agent whatever -f concat -i list
   with list content:
           file 'http://localhost:10000/1'
           file 'http://localhost:10000/2'
           ...

   But ffmpeg just ignored the user-agent option and sent the default one, how
   could I set http protocol related options when using the concat demuxer?

   Thanks!