Stage building failed

I got two stages, b1 and b2, b1 run first and then b2. At b1 I updated the repo, but at b2, it just failed to clone the update in b1. Is there any wrong with my operation? Or I missed something.

I thought it was supposed to run properly.

travis seems just pulls the last committed index. I skipped the updated in the jobs. I have to pull the second time to get the update.