git clone via SSH is not working with proxy config

Issue

• My build failed due to following error.

# oc get pods
NAME             READY     STATUS      RESTARTS   AGE
test01-1-build   0/1       Error       0          1h

# oc logs -f test01-1-build
The Build "test01-1" is invalid.
spec.source.git.uri: Invalid value: "ssh://<INTERNAL_GIT_URL>/foo/bar.git`": only http:// and https:// GIT protocols are allowed with HTTP or HTTPS proxy set

• I confirmed that it is possible to git clone ssh://<INTERNAL_GIT_URL>/foo/bar.git via ssh, but why I am getting above error?