[Android repo]How to fix error "bad object" using "repo sync"

Traceback (most recent call last):
File "/opt/nfs/user/Android-User-land/.repo/repo/main.py", line 366, in
_Main(sys.argv[1:])
File "/opt/nfs/user/Android-User-land/.repo/repo/main.py", line 346, in _Main
result = repo._Run(argv) or 0
File "/opt/nfs/user/Android-User-land/.repo/repo/main.py", line 137, in _Run
result = cmd.Execute(copts, cargs)
File "/opt/nfs/user/Android-User-land/.repo/repo/subcmds/sync.py", line 399, in Execute
if mp.HasChanges:
File "/opt/nfs/user/Android-User-land/.repo/repo/project.py", line 2115, in HasChanges
elif self._revlist(not_rev(HEAD), revid):
File "/opt/nfs/user/Android-User-land/.repo/repo/project.py", line 1772, in _revlist
return self.work_git.rev_list(*a, **kw)
File "/opt/nfs/user/Android-User-land/.repo/repo/project.py", line 1917, in rev_list
p.stderr))
error.GitError: manifests rev-list ('^HEAD', '1dc4025414e169c4751dd308f80d30723c2055b8', '--'): fatal: bad object 1dc4025414e169c4751dd308f80d30723c2055b8

Maybe you copy the Android source code,look like the copy is incomplete or damaged the files under the .repo directory.
Please copy it again and try again.