rollback stack before executing ensure clause.

src/vm.c

@@ -1219,9 +1219,9 @@ mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
         while (ci[0].ridx == ci[-1].ridx) {
           cipop(mrb);
           ci = mrb->ci;
+          mrb->stack = mrb->stbase + ci[1].stackidx;
           if (ci[1].acc < 0 && prev_jmp) {
             mrb->jmp = prev_jmp;
-            mrb->stack = mrb->stbase + ci[1].stackidx;
             longjmp(*(jmp_buf*)mrb->jmp, 1);
           }
           while (eidx > mrb->ci->eidx) {

test/t/exception.rb

@@ -315,6 +315,33 @@ assert('Exception 18') do
   end == 3
 end
 
+assert('Exception 19') do
+  class Class4Exception19
+    def a
+      r = @e = false
+      begin
+        b
+      rescue
+        r = self.z
+      end
+      [ r, @e ]
+    end
+  
+    def b
+      begin
+        1 * "b"
+      ensure
+        @e = self.z
+      end
+    end
+  
+    def z
+      true
+    end
+  end
+  Class4Exception19.new.a == [true,  true]
+end
+
 assert('Exception#inspect without message') do
   Exception.new.inspect
 end