Facinge update error

after giving the bench update command from cd frappe-bench/ then getting this error.what can I do? my image version

INFO:bench.utils:updating bench

error: cannot open .git/FETCH_HEAD: Permission denied

Traceback (most recent call last):
File “/usr/local/bin/bench”, line 9, in
load_entry_point(‘bench==0.92’, ‘console_scripts’, ‘bench’)()
File “/home/frappe/bench-repo/bench/cli.py”, line 40, in cli
File “/usr/local/lib/python2.7/dist-packages/click/core.py”, line 716, in call
return self.main(*args, **kwargs)
File “/usr/local/lib/python2.7/dist-packages/click/core.py”, line 696, in main
rv = self.invoke(ctx)
File “/usr/local/lib/python2.7/dist-packages/click/core.py”, line 1060, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File “/usr/local/lib/python2.7/dist-packages/click/core.py”, line 889, in invoke
return ctx.invoke(self.callback, **ctx.params)
File “/usr/local/lib/python2.7/dist-packages/click/core.py”, line 534, in invoke
return callback(*args, **kwargs)
File “/home/frappe/bench-repo/bench/commands/update.py”, line 34, in update
File “/home/frappe/bench-repo/bench/utils.py”, line 194, in update_bench
exec_cmd(“git pull”, cwd=cwd)
File “/home/frappe/bench-repo/bench/utils.py”, line 100, in exec_cmd
raise CommandFailedError(cmd)
bench.utils.CommandFailedError: git pull

Seems like a directory permission issue.
Try to set permissions using chown -R frappe ~/bench-repo