Fixes the checkpoint test.
Fixes the checkpoint test.

Summary:
Diff D5224410 initializes the should_stop_blob explicitly. With that, we will
have one more blob when executing the job. Adjusts the check accordingly.

Reviewed By: azzolini

Differential Revision: D5228398

fbshipit-source-id: 439b186c30b0b1d0e41e513babbcccd85e7a1b4a

caffe2/caffe2,xzturn/caffe2,pietern/caffe2,Yangqing/caffe2,sf-wind/caffe2,davinwang/caffe2,davinwang/caffe2,davinwang/caffe2,Yangqing/caffe2,bwasti/caffe2,sf-wind/caffe2,bwasti/caffe2,sf-wind/caffe2,pietern/caffe2,bwasti/caffe2,davinwang/caffe2,bwasti/caffe2,sf-wind/caffe2,xzturn/caffe2,xzturn/caffe2,Yangqing/caffe2,pietern/caffe2,sf-wind/caffe2,davinwang/caffe2,pietern/caffe2,bwasti/caffe2,xzturn/caffe2,Yangqing/caffe2,Yangqing/caffe2,pietern/caffe2,xzturn/caffe2