NoMethodError undefined method `zero?' for nil:NilClass (http 500)

Version: sameersbn/gitlab:9.4.3

From https://x.x.x.x:10443/admin/health_check
https://x.x.x.x:10443/-/readiness?token=6UQ1P7jmUhyhEYUefsBH

if you need additional information please ask.

==> gitlab/production.log <==
Started GET "/-/readiness?token=6UQ1P7jmUhyhEYUefsBH" for x.x.x.x at 2017-08-09 21:03:44 +0000
Processing by HealthController#readiness as HTML
  Parameters: {"token"=>"6UQ1P7jmUhyhEYUefsBH"}
Completed 500 Internal Server Error in 15ms (ActiveRecord: 0.4ms)

NoMethodError (undefined method `zero?' for nil:NilClass):
  lib/gitlab/health_checks/fs_shards_check.rb:89:in `delete_test_file'
  lib/gitlab/health_checks/fs_shards_check.rb:73:in `with_temp_file'
  lib/gitlab/health_checks/fs_shards_check.rb:16:in `block in readiness'
  lib/gitlab/health_checks/fs_shards_check.rb:11:in `map'
  lib/gitlab/health_checks/fs_shards_check.rb:11:in `readiness'
  app/controllers/health_controller.rb:12:in `block in readiness'
  app/controllers/health_controller.rb:12:in `map'
  app/controllers/health_controller.rb:12:in `readiness'
  lib/gitlab/performance_bar/peek_performance_bar_with_rack_body.rb:16:in `call'
  lib/gitlab/middleware/multipart.rb:93:in `call'
  lib/gitlab/request_profiler/middleware.rb:14:in `call'
  lib/gitlab/metrics/requests_rack_middleware.rb:27:in `call'


==> gitlab/gitlab-workhorse.log <==
x.x.x.x:10443 127.0.0.1:57948 - - [2017-08-09 21:20:53.46570548 +0000 UTC] "GET /-/readiness?token=6UQ1P7jmUhyhEYUefsBH HTTP/1.1" 500 2911 "" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0" 0.038110


==> nginx/gitlab_access.log <==
x.x.x.x - - [09/Aug/2017:21:20:53 +0000] "GET /-/readiness?token=6UQ1P7jmUhyhEYUefsBH HTTP/1.1" 500 2911 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0"

Start in lib/gitlab/health_checks/fs_shards_check.rb around lines 73 and 89, then review the readiness flow in app/controllers/health_controller.rb:12. Reproduce the GET /-/readiness request against the reported GitLab version and trace the nil value causing the NoMethodError. Done means the readiness check no longer returns HTTP 500 for this case.