I have what looks like the same problem.
Distro: Archlinux (i686)
libtorrent: 0.15.0
deluge: 1.2.3
glibc: 2.11.1

$ gdb --args python /usr/bin/deluged -l deluged-debug-7.log -L debug -d
GNU gdb (GDB) 7.1
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i686-pc-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /usr/bin/python...(no debugging symbols found)...done.
(gdb) run
Starting program: /usr/bin/python /usr/bin/deluged -l deluged-debug-7.log -L debug -d
[Thread debugging using libthread_db enabled]
[New Thread 0xb6f3bb70 (LWP 7309)]
[New Thread 0xb673ab70 (LWP 7310)]
[New Thread 0xb5f39b70 (LWP 7313)]
[New Thread 0xb536cb70 (LWP 7314)]
[New Thread 0xb4b6bb70 (LWP 7315)]
python: malloc.c:3951: __libc_valloc: Assertion `!p || ((((mchunkptr)((char*)(p) - 2*(sizeof(size_t)))))->size & 0x2) || ar_ptr == (((((mchunkptr)((char*)(p) - 2*(sizeof(size_t)))))->size & 0x4) ? ((heap_info *)((unsigned long)(((mchunkptr)((char*)(p) - 2*(sizeof(size_t))))) & ~((2 * (512 * 1024))-1)))->ar_ptr : &main_arena)' failed.

Program received signal SIGABRT, Aborted.
[Switching to Thread 0xb6f3bb70 (LWP 7309)]
0xb7fe1424 in __kernel_vsyscall ()
(gdb) bt
#0  0xb7fe1424 in __kernel_vsyscall ()
#1  0xb7d33561 in raise () from /lib/libc.so.6
#2  0xb7d34d62 in abort () from /lib/libc.so.6
#3  0xb7d74d64 in __malloc_assert () from /lib/libc.so.6
#4  0xb7d7931b in valloc () from /lib/libc.so.6
#5  0xb723049d in libtorrent::page_aligned_allocator::malloc(unsigned int) () from /usr/lib/libtorrent-rasterbar.so.6
#6  0xb725cf8a in boost::pool<libtorrent::page_aligned_allocator>::ordered_malloc_need_resize() () from /usr/lib/libtorrent-rasterbar.so.6
#7  0xb7252b46 in libtorrent::disk_buffer_pool::allocate_buffer(char const*) () from /usr/lib/libtorrent-rasterbar.so.6
#8  0xb7253ece in libtorrent::disk_io_thread::read_into_piece(libtorrent::disk_io_thread::cached_piece_entry&, int, int, int, boost::unique_lock<boost::recursive_mutex>&) () from /usr/lib/libtorrent-rasterbar.so.6
#9  0xb7256d15 in libtorrent::disk_io_thread::copy_from_piece(std::_List_iterator<libtorrent::disk_io_thread::cached_piece_entry>, bool&, libtorrent::disk_io_job const&, boost::unique_lock<boost::recursive_mutex>&) () from /usr/lib/libtorrent-rasterbar.so.6
#10 0xb7257baa in libtorrent::disk_io_thread::try_read_from_cache(libtorrent::disk_io_job const&) ()
   from /usr/lib/libtorrent-rasterbar.so.6
#11 0xb72596a8 in libtorrent::disk_io_thread::operator()() () from /usr/lib/libtorrent-rasterbar.so.6
#12 0xb72604d3 in boost::detail::thread_data<boost::reference_wrapper<libtorrent::disk_io_thread> >::run() ()
   from /usr/lib/libtorrent-rasterbar.so.6
#13 0xb6fd0095 in thread_proxy () from /usr/lib/libboost_thread-mt.so.1.41.0
#14 0xb7e5594c in start_thread () from /lib/libpthread.so.0
#15 0xb7dd6eae in clone () from /lib/libc.so.6

Contents of deluged-debug-7.log: http://pastebin.com/Br7062Qm