The builds installed in the hosted clusters are having issues to git-clone repositories from external URLs where their CA are configured in the ca-bundle.crt from trsutedCA section:

 spec:
    configuration:
      apiServer:
       [...]
      proxy:
        trustedCA:
          name: user-ca-bundle <---

In traditional OCP implementations, the *-global-ca configmap is installed in the same namespace from the build and the ca-bundle.crt is injected into this configmap. In hosted clusters the configmap is being created empty: 

$ oc get cm -n <app-namespace> <build-name>-global-ca  -oyaml
apiVersion: v1
data:
  ca-bundle.crt: ""


As mentioned, the user-ca-bundle has the certificates configured:

$ oc get cm -n openshift-config user-ca-bundle -oyaml
apiVersion: v1
data:
  ca-bundle.crt: |
    -----BEGIN CERTIFICATE----- <---

Easily

1. Install hosted cluster with trustedCA configmap
2. Run a build in the hosted cluster
3. Check the global-ca configmap

global-ca is empty

global-ca injects the ca-bundle.crt properly