Fix a segfault in previous commit (caught by testing).
Fix a segfault in previous commit (caught by testing).

For spaces with subspaces, or when performing transfers, it assumed an entry
would be in a map when, in fact, it was not.  This would lead to a NULL ptr
dereference.  Caught by the replication-stress-test.

cactorium/HyperDex,jtk54/HyperDex,rescrv/HyperDex,rescrv/HyperDex,pombredanne/HyperDex,vashstorm/HyperDex,UIKit0/HyperDex,vashstorm/HyperDex,rescrv/HyperDex,jtk54/HyperDex,pombredanne/HyperDex,jtk54/HyperDex,tempbottle/HyperDex,vashstorm/HyperDex,vashstorm/HyperDex,rescrv/HyperDex,vashstorm/HyperDex,cactorium/HyperDex,UIKit0/HyperDex,tempbottle/HyperDex,tempbottle/HyperDex,pombredanne/HyperDex,UIKit0/HyperDex,vashstorm/HyperDex,vashstorm/HyperDex,UIKit0/HyperDex,pombredanne/HyperDex,tempbottle/HyperDex,tempbottle/HyperDex,tempbottle/HyperDex,rescrv/HyperDex,UIKit0/HyperDex,pombredanne/HyperDex,jtk54/HyperDex,jtk54/HyperDex,pombredanne/HyperDex,cactorium/HyperDex,tempbottle/HyperDex,tempbottle/HyperDex,jtk54/HyperDex,cactorium/HyperDex,tempbottle/HyperDex,vashstorm/HyperDex,UIKit0/HyperDex,cactorium/HyperDex,vashstorm/HyperDex,pombredanne/HyperDex,rescrv/HyperDex,jtk54/HyperDex,UIKit0/HyperDex,cactorium/HyperDex,rescrv/HyperDex,cactorium/HyperDex,UIKit0/HyperDex,pombredanne/HyperDex,jtk54/HyperDex,cactorium/HyperDex,pombredanne/HyperDex,UIKit0/HyperDex,cactorium/HyperDex,rescrv/HyperDex,jtk54/HyperDex,rescrv/HyperDex