fix unbound variable release.sh

hack/lib/golang.sh

@@ -165,6 +165,8 @@ kube::golang::dedup() {
 # KUBE_SUPPORTED* vars at the top of this file.
 declare -a -g KUBE_SERVER_PLATFORMS
 declare -a -g KUBE_CLIENT_PLATFORMS
+declare -a -g KUBE_NODE_PLATFORMS
+declare -a -g KUBE_TEST_PLATFORMS
 kube::golang::setup_platforms() {
   if [[ -n "${KUBE_BUILD_PLATFORMS:-}" ]]; then
     # KUBE_BUILD_PLATFORMS needs to be read into an array before the next
@@ -206,19 +208,22 @@ kube::golang::setup_platforms() {
   elif [[ "${KUBE_FASTBUILD:-}" == "true" ]]; then
     KUBE_SERVER_PLATFORMS=(linux/amd64)
     readonly KUBE_SERVER_PLATFORMS
-    readonly KUBE_NODE_PLATFORMS=(linux/amd64)
+    KUBE_NODE_PLATFORMS=(linux/amd64)
+    readonly KUBE_NODE_PLATFORMS
     if [[ "${KUBE_BUILDER_OS:-}" == "darwin"* ]]; then
-      readonly KUBE_TEST_PLATFORMS=(
+      KUBE_TEST_PLATFORMS=(
         darwin/amd64
         linux/amd64
       )
+      readonly KUBE_TEST_PLATFORMS
       KUBE_CLIENT_PLATFORMS=(
         darwin/amd64
         linux/amd64
       ) 
       readonly KUBE_CLIENT_PLATFORMS
     else
-      readonly KUBE_TEST_PLATFORMS=(linux/amd64)
+      KUBE_TEST_PLATFORMS=(linux/amd64)
+      readonly KUBE_TEST_PLATFORMS
       KUBE_CLIENT_PLATFORMS=(linux/amd64)
       readonly KUBE_CLIENT_PLATFORMS
     fi