Fix deadlock when there are no modules
Fix deadlock when there are no modules

Change-Id: Ibfc1190f2b5ac3c3445d40f1b5dd0cd782e63dfd

colincross/blueprint,google/blueprint,yuhangwang/blueprint,colincross/blueprint,google/blueprint,danw/blueprint,danw/blueprint,Tiger66639/blueprint,Tiger66639/blueprint,jgennis/blueprint,jgennis/blueprint,yuhangwang/blueprint