performStackOperation should return the latest stack
performStackOperation should return the latest stack

We want to return the latest stack after performing a stack operation
and still holding the lock. This lets us trust the information within
the stack outputs.

iserko/empire,remind101/empire,iserko/empire,remind101/empire,mhahn/empire,iserko/empire,mhahn/empire,mhahn/empire,remind101/empire