What happens if you manually run the pg_dump command quoted above against a running 9.1 server, outside of the context of pg_upgrade? (Your port will be probably be different from 50432)
If that still crashes, What if you drop the --binary-upgrade option? The --format=custom option?
I started the 9.1 server normally and ran the above pg_dump (with the appropriate port for that instance).
So it seem the -binary-upgrade option has caused some problem. And the same crash happens regardless of whether i use the 9.1's or 9.3's pg_dump.
You need to install the debugging symbols, which I have no experience doing under Ubuntu, but it should be easy to find instructions for. Or you could compile pg_dump from source, after configuring with --enable-debug.
I can handle the debug symbols build. I'll see what i can do if the pg_dump information doesn't lead anywhere useful.