gcloud compute instance-groups managed describe <instance-group-name> doesn't work if not specifying --zone #2899

gcloud compute instance-groups managed describe <instance-group-name>

± gcloud beta compute instance-groups managed describe gke-pen-default-pool-694be9cd-grp --format json
For the following instance group managers:
 - [gke-pen-default-pool-694be9cd-grp]
choose a zone or region:
 [1] zone: asia-east1-b
 [2] zone: asia-east1-c
 [3] zone: asia-east1-a
 [4] zone: asia-northeast1-c
 [5] zone: asia-northeast1-b
 [6] zone: asia-northeast1-a
 [7] zone: europe-west1-c
 [8] zone: europe-west1-b
 [9] zone: europe-west1-d
 [10] zone: us-central1-a
 [11] zone: us-central1-c
 [12] zone: us-central1-b
 [13] zone: us-central1-f
 [14] zone: us-east1-c
 [15] zone: us-east1-d
 [16] zone: us-east1-b
 [17] zone: us-west1-a
 [18] zone: us-west1-b
 [19] region: asia-east1
 [20] region: asia-northeast1
 [21] region: europe-west1
 [22] region: us-central1
 [23] region: us-east1
 [24] region: us-west1
Please enter your numeric choice:  1

ERROR: (gcloud.beta.compute.instance-groups.managed.describe) Could not fetch resource:
 - The resource 'projects/<project-id>/zones/asia-east1-a/instanceGroupManagers/gke-pen-default-pool-694be9cd-grp' was not found

± uname -a
Darwin CA1596.local 15.6.0 Darwin Kernel Version 15.6.0: Wed Nov  2 20:30:56 PDT 2016; root:xnu-3248.60.11.1.2~2/RELEASE_X86_64 x86_64

± python --version
Python 2.7.12

± pip show google-cloud
You are using pip version 8.1.2, however version 9.0.1 is available.