使用repo sync時，如果當前倉庫有檢出本地分支，假設為dev, 對應的遠端track分支為origin/dev。 而manifest.xml中指定的track分支為origin/master,那麼在repo sync時會自動將當前的dev分支的遠端track分支修改為origin/master, 不僅如此，同時還會將origin/master上的修改rebase到本地的這個dev分支上。

projectA/: manifest switched refs/heads/dev...master
project projectA/
First, rewinding head to replay your work on top of it...
Applying: y
 

diff --git a/project.py b/project.py
index 22e4a5d..3ce6500 100644
--- a/project.py
+++ b/project.py
@@ -1169,6 +1169,8 @@ class Project(object):
         syncbuf.info(self,
                      'manifest no longer tracks %s',
                      branch.merge)
+      syncbuf.fail(self, "branch is not consistent:%s, %s" %(branch.merge, self.revisionExpr))  
+      return
 
     if cnt_mine < len(local_changes):
       # Upstream rebased.  Not everything in HEAD