I believe this should be fixed in:
commit 5e278c19c752d65fdc1da1ceb599b091f71a4b4b
Author: Stefano Sabatini <stefasab@gmail.com>
Date: Fri Nov 22 12:49:05 2013 +0100
lavf/segment: add segment_list_entry_prefix option
This option allows to add a prefix to the segment list entry filenames.
Also set by default the list entry filenames to the corresponding
segment basename, consistent with the HLS muxer.
Based on an idea by Steven Liu <lingjiujianke@gmail.com>.
The new option allows to set the prefix to use for the playlist file.