Make verify-api-groups.sh not depend on GOPATH

This script quiently depended on being under a GOPATH, and failed
completely when it was not.  This change sorts the input (to make
comparing results easier) and operates on files, rather than packages
until the last moment when we add back the package prefix.

Verified by instrumenting the code and comparing runs inside and outside
of GOPATH.

Author: thockin

hack/verify-api-groups.sh

@@ -23,12 +23,11 @@ set -o pipefail
 
 KUBE_ROOT=$(dirname "${BASH_SOURCE[0]}")/..
 source "${KUBE_ROOT}/hack/lib/init.sh"
-prefix="${KUBE_ROOT%"k8s.io/kubernetes"}"
 
 register_files=()
-while IFS= read -d $'\0' -r file ; do
+while read -r file ; do
 	register_files+=("${file}")
-done < <(find "${KUBE_ROOT}"/pkg/apis -name register.go -print0)
+done < <(find pkg/apis -name register.go | sort)
 
 # every register file should contain a GroupName.  Gather the different representations.
 # 1. group directory name for client gen
@@ -38,9 +37,8 @@ group_dirnames=()
 external_group_versions=()
 expected_install_packages=()
 for register_file in "${register_files[@]}"; do
-	package="${register_file#"${prefix}"}"
-	package="${package%"/register.go"}"
-	group_dirname="${package#"k8s.io/kubernetes/pkg/apis/"}"
+	package="${register_file%"/register.go"}"
+	group_dirname="${package#"pkg/apis/"}"
 	group_dirname="${group_dirname%%"/*"}"
 	group_name=""
 	if grep -q 'GroupName = "' "${register_file}"; then
@@ -50,11 +48,11 @@ for register_file in "${register_files[@]}"; do
 		exit 1
 	fi
 
-	# does the dirname doesn't have a slash, then it's the internal package.
-	# if does have one, then its an external
+	# If the dirname doesn't have a slash, then it's the internal package.
+	# if does have one, then it's versioned (e.g. foobar/v1).
 	if [[ "${group_dirname#*'/'}" == "${group_dirname}" ]]; then
 		group_dirnames+=("${group_dirname}")
-		expected_install_packages+=("${package}")
+		expected_install_packages+=("k8s.io/kubernetes/${package}")
 	else
 		version=$(echo "${group_dirname}" | cut -d/ -f2 -)
 		external_group_versions+=("${group_name}/${version}")