Updating .so files for functions?

I ran into a crash that was caused by the .so files used by postgres being overwritten ( see http://www.postgresql.org/message-id/CAAcYxUeduPhKXbDQ6ZTOhKGE+1A3cMrTQujSExC-tv4ac4ksUw@mail.gmail.com ), so that made me wonder what the rules are for updating .so files. I read through the documentation on C functions ( http://www.postgresql.org/docs/8.4/static/xfunc-c.html ) but didn't come to any firm answers.

Here's our current procedure:

2) Put new .so files in "version directory" (for example /path/to/funcs/1.23.1/ where old version was /path/to/funcs/1.23.0/)

3) Run "ALTER DATABASE <db_name> SET dynamic_library_path TO '/path/to/funcs/1.23.1:$libdir';"