https://github.com/kubernetes/kubernetes/pull/80827

Sally we need to pick Clayton's PR into oc. Ping me for how :-)

Merged in https://github.com/openshift/oc/pull/63 moving to qa.

Confirmed with latest oc version, the fix was missed :
[root@dhcp-140-138 yamlfile]# oc version --short 
Client Version: v4.2.0
Server Version: v1.14.0+5b18abc
OpenShift Version: 4.2.0-0.nightly-2019-08-21-210916


[root@dhcp-140-138 yamlfile]# oc get cm cmtest -o yaml 
apiVersion: v1
binaryData:
  bar: jmjKxUGNs/WqDQ==
data:
  foo: text value
kind: ConfigMap
metadata:
  creationTimestamp: "2019-08-22T08:49:11Z"
  name: cmtest
  namespace: zytest
  resourceVersion: "107431"
  selfLink: /api/v1/namespaces/zytest/configmaps/cmtest
  uid: b60f2f26-c4b9-11e9-b232-0a71a0132866
[root@dhcp-140-138 yamlfile]# oc extract cm/cmtest --to=-
# foo
text value

I tested with oc downloaded from latest available nightly (openshift-client-linux-4.2.0-0.nightly-2019-08-27-105356/oc)
oc extract is returning binaryData.  Please test again to confirm.  Thanks!

$ oc version --short
Client Version: v4.2.0-alpha.0-29-g6788d4a0
Server Version: v1.14.0+1801aa8
OpenShift Version: 4.2.0-0.ci-2019-08-26-085534

$ oc get cm cmtest -o yaml
apiVersion: v1
binaryData:
  bar: jmjKxUGNs/WqDQ==
data:
  foo: text value
kind: ConfigMap
metadata:
  creationTimestamp: "2019-08-27T21:05:58Z"
  name: cmtest
  namespace: bztest
  resourceVersion: "516496"
  selfLink: /api/v1/namespaces/bztest/configmaps/cmtest
  uid: 77c17e06-c90e-11e9-b72c-0658239c1cdc

$ oc extract cm/cmtest --to=-
# foo
text value
# bar
�h��A����

Sally :

     Thanks for feedback, I double confirmed , when use oc extract from nightly build we can extract the binarydata correctly:
[root@dhcp-140-138 ~]# oc extract cm/cmtest -n openshift-config --to=-
# foo
text value
# bar
�h��A����


But use oc installed by the yum repo, still miss the binaryData:
[root@dhcp-140-138 ~]# oc version 
Client Version: version.Info{Major:"4", Minor:"2+", GitVersion:"v4.2.0", GitCommit:"09eb70949", GitTreeState:"clean", BuildDate:"2019-08-27T22:29:56Z", GoVersion:"go1.12.8", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"13+", GitVersion:"v1.13.4+4b86cc5", GitCommit:"4b86cc5", GitTreeState:"clean", BuildDate:"2019-07-24T19:42:25Z", GoVersion:"go1.11.6", Compiler:"gc", Platform:"linux/amd64"}
OpenShift Version: 4.1.8

[root@dhcp-140-138 ~]# oc get cm cmtest -n openshift-config -o yaml 
apiVersion: v1
binaryData:
  bar: jmjKxUGNs/WqDQ==
data:
  foo: text value
kind: ConfigMap
metadata:
  creationTimestamp: "2019-08-28T01:25:03Z"
  name: cmtest
  namespace: openshift-config
  resourceVersion: "229540"
  selfLink: /api/v1/namespaces/openshift-config/configmaps/cmtest
  uid: a94c1cc8-c932-11e9-9ad5-024af6bb4588
[root@dhcp-140-138 ~]# oc extract cm/cmtest -n openshift-config --to=-
# foo
text value

Ah, I see, thanks for the info.  The rpm is indeed a bit behind (It shouldn't/won't be in near future, but with the recent split of oc from origin this is a side-effect).  The rpm should be up-to-date by tomorrow.  Since I've confirmed the recent payload has the fix, I'm confident there's nothing more to do on our end.  Please confirm the fix in the oc extracted from the latest payload, such as: https://openshift-release.svc.ci.openshift.org/releasestream/4.2.0-0.ci/release/4.2.0-0.ci-2019-08-28-123746   
Thanks!

Using oc extracted from 4.2.0-0.nightly-2019-08-28-235925, can't reproduce the issue:
[root@dhcp-140-138 ~]# oc get cm cmtest -o yaml 
apiVersion: v1
binaryData:
  bar: jmjKxUGNs/WqDQ==
data:
  foo: text value
kind: ConfigMap
metadata:
  creationTimestamp: "2019-08-29T02:17:00Z"
  name: cmtest
  namespace: zhouytm
  resourceVersion: "731052"
  selfLink: /api/v1/namespaces/zhouytm/configmaps/cmtest
  uid: 15724363-ca03-11e9-9fdd-06aa25ffd4c6
[root@dhcp-140-138 ~]# oc extract cm/cmtest --to=-
# foo
text value
# bar
�h��A����
[root@dhcp-140-138 ~]# oc version
Client Version: version.Info{Major:"", Minor:"", GitVersion:"openshift-clients-4.2.0-201908281419", GitCommit:"372c08a6a95e4ecc7c61dd16052fc12f6bca376c", GitTreeState:"clean", BuildDate:"2019-08-28T19:10:30Z", GoVersion:"go1.12.8", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"14+", GitVersion:"v1.14.0+e12dd85", GitCommit:"e12dd85", GitTreeState:"clean", BuildDate:"2019-08-27T23:04:55Z", GoVersion:"go1.12.8", Compiler:"gc", Platform:"linux/amd64"}

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2019:2922