Description of problem:


Version-Release number of selected component (if applicable):
master.20170830033416_aa4dab9 

How reproducible:
100%

Steps to Reproduce:
1.Add google compute Engine provider
2.From configuration refresh relationship and power states
3.

Actual results:
Refresh fails with error "no implicit conversion of nil into Array". see attached screenshot.

Expected results:
Refresh successful

Additional info:
production.log
[----] E, [2017-08-30T06:00:53.622484 #856:6bf134] ERROR -- : MIQ(ManageIQ::Providers::Google::CloudManager::Refresher#refresh) EMS: [gce_central], id: [2] Refresh failed
[----] E, [2017-08-30T06:00:53.623086 #856:6bf134] ERROR -- : [TypeError]: no implicit conversion of nil into Array  Method:[block in method_missing]
[----] E, [2017-08-30T06:00:53.623534 #856:6bf134] ERROR -- : /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/fog-google-0.5.3/lib/fog/compute/google/models/snapshots.rb:12:in `concat'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/fog-google-0.5.3/lib/fog/compute/google/models/snapshots.rb:12:in `block in all'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/fog-google-0.5.3/lib/fog/compute/google/models/snapshots.rb:10:in `loop'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/fog-google-0.5.3/lib/fog/compute/google/models/snapshots.rb:10:in `all'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/bundler/gems/manageiq-providers-google-2b326996ff57/app/models/manageiq/providers/google/cloud_manager/refresh_parser.rb:56:in `get_snapshots'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/bundler/gems/manageiq-providers-google-2b326996ff57/app/models/manageiq/providers/google/cloud_manager/refresh_parser.rb:26:in `ems_inv_to_hashes'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/bundler/gems/manageiq-providers-google-2b326996ff57/app/models/manageiq/providers/google/refresh_helper_methods.rb:39:in `ems_inv_to_hashes'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/bundler/gems/manageiq-providers-google-2b326996ff57/app/models/manageiq/providers/google/cloud_manager/refresher.rb:6:in `parse_legacy_inventory'
/var/www/miq/vmdb/app/models/ems_refresh/refreshers/ems_refresher_mixin.rb:158:in `block in parse_targeted_inventory'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/bundler/gems/manageiq-gems-pending-29bc8de18faf/lib/gems/pending/util/extensions/miq-benchmark.rb:11:in `realtime_store'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/bundler/gems/manageiq-gems-pending-29bc8de18faf/lib/gems/pending/util/extensions/miq-benchmark.rb:30:in `realtime_block'
/var/www/miq/vmdb/app/models/ems_refresh/refreshers/ems_refresher_mixin.rb:158:in `parse_targeted_inventory'
/var/www/miq/vmdb/app/models/ems_refresh/refreshers/ems_refresher_mixin.rb:88:in `block in refresh_targets_for_ems'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/bundler/gems/manageiq-gems-pending-29bc8de18faf/lib/gems/pending/util/extensions/miq-benchmark.rb:11:in `realtime_store'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/bundler/gems/manageiq-gems-pending-29bc8de18faf/lib/gems/pending/util/extensions/miq-benchmark.rb:30:in `realtime_block'
/var/www/miq/vmdb/app/models/ems_refresh/refreshers/ems_refresher_mixin.rb:87:in `refresh_targets_for_ems'
/var/www/miq/vmdb/app/models/ems_refresh/refreshers/ems_refresher_mixin.rb:24:in `block (2 levels) in refresh'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/bundler/gems/manageiq-gems-pending-29bc8de18faf/lib/gems/pending/util/extensions/miq-benchmark.rb:11:in `realtime_store'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/bundler/gems/manageiq-gems-pending-29bc8de18faf/lib/gems/pending/util/extensions/miq-benchmark.rb:30:in `realtime_block'
/var/www/miq/vmdb/app/models/ems_refresh/refreshers/ems_refresher_mixin.rb:24:in `block in refresh'
/var/www/miq/vmdb/app/models/ems_refresh/refreshers/ems_refresher_mixin.rb:14:in `each'
/var/www/miq/vmdb/app/models/ems_refresh/refreshers/ems_refresher_mixin.rb:14:in `refresh'
/var/www/miq/vmdb/app/models/manageiq/providers/base_manager/refresher.rb:9:in `refresh'
/var/www/miq/vmdb/app/models/ems_refresh.rb:97:in `block in refresh'
/var/www/miq/vmdb/app/models/ems_refresh.rb:96:in `each'
/var/www/miq/vmdb/app/models/ems_refresh.rb:96:in `refresh'
/var/www/miq/vmdb/app/models/miq_queue.rb:387:in `block in deliver'
/opt/rubies/ruby-2.3.1/lib/ruby/2.3.0/timeout.rb:91:in `block in timeout'
/opt/rubies/ruby-2.3.1/lib/ruby/2.3.0/timeout.rb:33:in `block in catch'
/opt/rubies/ruby-2.3.1/lib/ruby/2.3.0/timeout.rb:33:in `catch'
/opt/rubies/ruby-2.3.1/lib/ruby/2.3.0/timeout.rb:33:in `catch'
/opt/rubies/ruby-2.3.1/lib/ruby/2.3.0/timeout.rb:106:in `timeout'
/var/www/miq/vmdb/app/models/miq_queue.rb:386:in `deliver'
/var/www/miq/vmdb/app/models/miq_queue_worker_base/runner.rb:105:in `deliver_queue_message'
/var/www/miq/vmdb/app/models/miq_queue_worker_base/runner.rb:134:in `deliver_message'
/var/www/miq/vmdb/app/models/miq_queue_worker_base/runner.rb:152:in `block in do_work'
/var/www/miq/vmdb/app/models/miq_queue_worker_base/runner.rb:146:in `loop'
/var/www/miq/vmdb/app/models/miq_queue_worker_base/runner.rb:146:in `do_work'
/var/www/miq/vmdb/app/models/miq_worker/runner.rb:331:in `block in do_work_loop'
/var/www/miq/vmdb/app/models/miq_worker/runner.rb:328:in `loop'
/var/www/miq/vmdb/app/models/miq_worker/runner.rb:328:in `do_work_loop'
/var/www/miq/vmdb/app/models/miq_worker/runner.rb:155:in `run'
/var/www/miq/vmdb/app/models/miq_worker/runner.rb:129:in `start'
/var/www/miq/vmdb/app/models/miq_worker/runner.rb:22:in `start_worker'
/var/www/miq/vmdb/app/models/miq_worker.rb:357:in `block in start_runner_via_fork'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/nakayoshi_fork-0.0.3/lib/nakayoshi_fork.rb:24:in `fork'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/nakayoshi_fork-0.0.3/lib/nakayoshi_fork.rb:24:in `fork'
/var/www/miq/vmdb/app/models/miq_worker.rb:355:in `start_runner_via_fork'
/var/www/miq/vmdb/app/models/miq_worker.rb:349:in `start_runner'
/var/www/miq/vmdb/app/models/miq_worker.rb:383:in `start'
/var/www/miq/vmdb/app/models/miq_worker.rb:274:in `start_worker'
/var/www/miq/vmdb/app/models/mixins/per_ems_worker_mixin.rb:68:in `start_worker_for_ems'
/var/www/miq/vmdb/app/models/mixins/per_ems_worker_mixin.rb:46:in `block in sync_workers'
/var/www/miq/vmdb/app/models/mixins/per_ems_worker_mixin.rb:45:in `each'
/var/www/miq/vmdb/app/models/mixins/per_ems_worker_mixin.rb:45:in `sync_workers'
/var/www/miq/vmdb/app/models/miq_server/worker_management/monitor.rb:53:in `block in sync_workers'
/var/www/miq/vmdb/app/models/miq_server/worker_management/monitor.rb:50:in `each'
/var/www/miq/vmdb/app/models/miq_server/worker_management/monitor.rb:50:in `sync_workers'
/var/www/miq/vmdb/app/models/miq_server/worker_management/monitor.rb:22:in `monitor_workers'
/var/www/miq/vmdb/app/models/miq_server.rb:346:in `block in monitor'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/bundler/gems/manageiq-gems-pending-29bc8de18faf/lib/gems/pending/util/extensions/miq-benchmark.rb:11:in `realtime_store'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/bundler/gems/manageiq-gems-pending-29bc8de18faf/lib/gems/pending/util/extensions/miq-benchmark.rb:30:in `realtime_block'
/var/www/miq/vmdb/app/models/miq_server.rb:346:in `monitor'
/var/www/miq/vmdb/app/models/miq_server.rb:368:in `block (2 levels) in monitor_loop'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/bundler/gems/manageiq-gems-pending-29bc8de18faf/lib/gems/pending/util/extensions/miq-benchmark.rb:11:in `realtime_store'
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/bundler/gems/manageiq-gems-pending-29bc8de18faf/lib/gems/pending/util/extensions/miq-benchmark.rb:30:in `realtime_block'
/var/www/miq/vmdb/app/models/miq_server.rb:368:in `block in monitor_loop'
/var/www/miq/vmdb/app/models/miq_server.rb:367:in `loop'
/var/www/miq/vmdb/app/models/miq_server.rb:367:in `monitor_loop'
/var/www/miq/vmdb/app/models/miq_server.rb:250:in `start'
/var/www/miq/vmdb/lib/workers/evm_server.rb:27:in `start'
/var/www/miq/vmdb/lib/workers/evm_server.rb:48:in `start'
/var/www/miq/vmdb/lib/workers/bin/evm_server.rb:4:in `<main>'