Fix forking state from memory (#407)

* import ForkState before use

* Fix ForkState behavior

manticore/core/memory.py

@@ -954,7 +954,8 @@ class SMemory(Memory):
                 condition = False
                 for base in e.solutions:
                     condition = Operators.OR(address == base, condition )
-                raise ForkState(condition)
+                from .state import ForkState
+                raise ForkState("Forking state on incomplete result", condition)
 
             #So here we have all potential solutions to address
             assert len(solutions) > 0

manticore/core/state.py

@@ -3,7 +3,7 @@ import copy
 import logging
 from collections import OrderedDict
 
-from .smtlib import solver
+from .smtlib import solver, Bool
 from ..utils.helpers import issymbolic
 from ..utils.event import Signal, forward_signals