[racket] bug fixes since 5.2.1

Are there any big known bugs in 5.2.1 that have since been fixed?

(The reason I ask is that I have a large system that works with 5.2.1 
but not with 5.3.2.  I still need to debug the cause of this, but for 
various reasons I think we'll probably stick with 5.2.1 for now, unless 
there's a good correctness/reliability reason to move past 5.2.1.  Most 
of this software is already known to work well under 5.2.1, and the only 
code not yet proven under 5.2.1 is some new uses of the Racket "db" 
library.)

Neil V.