testing: use runtime/debug to format panics
testing: use runtime/debug to format panics

Sorry, Mercurial failed me.

TBR=r, dsymonds
CC=golang-dev
http://codereview.appspot.com/5649080

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang