http://blog.kowalczyk.info/article/Gdb-basics.html

It is difficult to display the frame you're in while debugging a core
dump in python 3.0 (when in a core dump, you can't run functions, and
thus cannot use many of the normal methods of displaying unicode). 

Martin van Loewis discovered this gdb function (linked), "pu", which
prints out unicode strings.  The way it does so is a bit kludgy, but I
think it is at least the start of a solution.  Perhaps it can be
included in .gdbinit?