Clone frappe,erpnext and custom-app install?

I have got conflict while pulling frappe from git repository to production server.

So I have removed Frappe, eprnext and my custom-app folder in the production server.

Then i cloned all these three from git repository to production server.
And I installed all these three apps using the command
bench --site sitename install-app app-name

But when i did bench update from frappe-bench folder, i am having the following error!

root@ubuntu-2gb-lon1-01:/home/erpnext/frappe-bench# bench update
INFO:bench.utils:updating bench
Already up-to-date.
error: cannot open .git/FETCH_HEAD: Permission denied

error: cannot open .git/FETCH_HEAD: Permission denied

Requirement already satisfied: Pillow in ./env/lib/python2.7/site-packages frappe
error: cannot open .git/FETCH_HEAD: Permission denied

Traceback (most recent call last):
  File "/usr/local/bin/bench", line 9, in <module>
    load_entry_point('bench', 'console_scripts', 'bench')()
  File "/home/erpnext/bench-repo/bench/", line 40, in cli
  File "/usr/local/lib/python2.7/dist-packages/click/", line 716, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/click/", line 696, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python2.7/dist-packages/click/", line 1060, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python2.7/dist-packages/click/", line 889, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python2.7/dist-packages/click/", line 534, in invoke
    return callback(*args, **kwargs)
  File "/home/erpnext/bench-repo/bench/commands/", line 62, in update
    _update(pull, patch, build, bench, auto, restart_supervisor, requirements, no_backup, upgrade, force=force, reset=reset)
  File "/home/erpnext/bench-repo/bench/commands/", line 78, in _update
    pull_all_apps(bench_path=bench_path, reset=reset)
  File "/home/erpnext/bench-repo/bench/", line 146, in pull_all_apps
    remote=remote, branch=get_current_branch(app, bench_path=bench_path)), cwd=app_dir)
  File "/home/erpnext/bench-repo/bench/", line 127, in exec_cmd
    raise CommandFailedError(cmd)
bench.utils.CommandFailedError: git pull  upstream master

Anybody know how this issue can be reolved?

hope this helps github - Trying to git pull with error: cannot open .git/FETCH_HEAD: Permission denied - Stack Overflow