Do not shadow exceptions

Author: pitr-ch

lib/concurrent/edge/promises.rb

@@ -1382,8 +1382,8 @@ def self.new_blocked_by1(blocker, *args, &block)
         blocker_delayed = blocker.promise.delayed
         delayed         = blocker_delayed ? LockFreeStack.new.push(blocker_delayed) : nil
         promise         = new(delayed, 1, *args, &block)
-      ensure
         blocker.add_callback :callback_notify_blocked, promise, 0
+        promise
       end
 
       def self.new_blocked_by2(blocker1, blocker2, *args, &block)
@@ -1400,16 +1400,16 @@ def self.new_blocked_by2(blocker1, blocker2, *args, &block)
                              blocker_delayed2 ? LockFreeStack.of1(blocker_delayed2) : nil
                            end
         promise          = new(delayed, 2, *args, &block)
-      ensure
         blocker1.add_callback :callback_notify_blocked, promise, 0
         blocker2.add_callback :callback_notify_blocked, promise, 1
+        promise
       end
 
       def self.new_blocked_by(blockers, *args, &block)
         delayed = blockers.reduce(nil, &method(:add_delayed))
         promise = new(delayed, blockers.size, *args, &block)
-      ensure
         blockers.each_with_index { |f, i| f.add_callback :callback_notify_blocked, promise, i }
+        promise
       end
 
       def self.add_delayed(delayed, blocker)