Use git archive to produce kubernetes-src.tar.gz when possible

build/lib/release.sh

@@ -98,7 +98,11 @@ function kube::release::package_tarballs() {
 
 # Package the source code we built, for compliance/licensing/audit/yadda.
 function kube::release::package_src_tarball() {
+  local -r src_tarball="${RELEASE_TARS}/kubernetes-src.tar.gz"
   kube::log::status "Building tarball: src"
+  if [[ "${KUBE_GIT_TREE_STATE-}" == "clean" ]]; then
+    git archive -o "${src_tarball}" HEAD
+  else
     local source_files=(
       $(cd "${KUBE_ROOT}" && find . -mindepth 1 -maxdepth 1 \
         -not \( \
@@ -109,7 +113,8 @@ function kube::release::package_src_tarball() {
           \) -prune \
         \))
     )
-  "${TAR}" czf "${RELEASE_TARS}/kubernetes-src.tar.gz" -C "${KUBE_ROOT}" "${source_files[@]}"
+    "${TAR}" czf "${src_tarball}" -C "${KUBE_ROOT}" "${source_files[@]}"
+  fi
 }
 
 # Package up all of the cross compiled clients. Over time this should grow into