make mark-new-release.sh do branching and tell you exactly what to do next

We keep getting tags and branches wonky.  This will land

v0.14.0 as an ancestor of master
v0.14.1 will NOT be an ancestor of master

I can do the later, it only a touch of git gymnastics, not really hard, but
we only occasionably do that today. (0.13.1 is an ancestor of master,
but 0.13.2 is not)

build/mark-new-version.sh

@@ -24,7 +24,7 @@ KUBE_ROOT=$(dirname "${BASH_SOURCE}")/..
 
 NEW_VERSION=${1-}
 
-VERSION_REGEX="v([0-9]+).([0-9]+(.[0-9]+)?)"
+VERSION_REGEX="v([0-9]+).([0-9]+)(.([0-9]+))?"
 [[ ${NEW_VERSION} =~ $VERSION_REGEX ]] || {
   echo "!!! You must specify the version in the form of '$VERSION_REGEX'" >&2
   exit 1
@@ -32,6 +32,13 @@ VERSION_REGEX="v([0-9]+).([0-9]+(.[0-9]+)?)"
 
 VERSION_MAJOR="${BASH_REMATCH[1]}"
 VERSION_MINOR="${BASH_REMATCH[2]}"
+VERSION_PATCH="${BASH_REMATCH[4]}"
+
+# force .0 if no patch version specified
+if [[ -z ${VERSION_PATCH:-} ]]; then
+  VERSION_PATCH="0"
+  NEW_VERSION="${NEW_VERSION}.0"
+fi
 
 if ! git diff-index --quiet --cached HEAD; then
   echo "!!! You must not have any changes in your index when running this command"
@@ -43,6 +50,16 @@ if ! git diff-files --quiet pkg/version/base.go; then
   exit 1
 fi
 
+release_branch="release-${VERSION_MAJOR}.${VERSION_MINOR}"
+
+if [[ "${VERSION_PATCH}" != "0" ]]; then
+  branch=$(git rev-parse --abbrev-ref HEAD)
+  if [[ ${branch} != "${release_branch}" ]]; then
+    echo "!!! You are trying to tag to an existing minor release but are not on the release branch: ${release_branch}"
+    exit 1
+  fi
+fi
+
 SED=sed
 if which gsed &>/dev/null; then
   SED=gsed
@@ -54,8 +71,8 @@ fi
 VERSION_FILE="${KUBE_ROOT}/pkg/version/base.go"
 
 echo "+++ Updating to ${NEW_VERSION}"
-"$SED" -r -i -e "s/gitMajor\s+string = \"[^\"]*\"/gitMajor string = \"$VERSION_MAJOR\"/" "${VERSION_FILE}"
+"$SED" -r -i -e "s/gitMajor\s+string = \"[^\"]*\"/gitMajor string = \"${VERSION_MAJOR}\"/" "${VERSION_FILE}"
-"$SED" -r -i -e "s/gitMinor\s+string = \"[^\"]*\"/gitMinor string = \"$VERSION_MINOR\"/" "${VERSION_FILE}"
+"$SED" -r -i -e "s/gitMinor\s+string = \"[^\"]*\"/gitMinor string = \"${VERSION_MINOR}.${VERSION_PATCH}\"/" "${VERSION_FILE}"
 "$SED" -r -i -e "s/gitVersion\s+string = \"[^\"]*\"/gitVersion string = \"$NEW_VERSION\"/" "${VERSION_FILE}"
 gofmt -s -w "${VERSION_FILE}"
 
@@ -67,11 +84,30 @@ echo "+++ Tagging version"
 git tag -a -m "Kubernetes version $NEW_VERSION" "${NEW_VERSION}"
 
 echo "+++ Updating to ${NEW_VERSION}-dev"
-"$SED" -r -i -e "s/gitMajor\s+string = \"[^\"]*\"/gitMajor string = \"$VERSION_MAJOR\"/" "${VERSION_FILE}"
+"$SED" -r -i -e "s/gitMajor\s+string = \"[^\"]*\"/gitMajor string = \"${VERSION_MAJOR}\"/" "${VERSION_FILE}"
-"$SED" -r -i -e "s/gitMinor\s+string = \"[^\"]*\"/gitMinor string = \"$VERSION_MINOR\+\"/" "${VERSION_FILE}"
+"$SED" -r -i -e "s/gitMinor\s+string = \"[^\"]*\"/gitMinor string = \"${VERSION_MINOR}.${VERSION_PATCH}\+\"/" "${VERSION_FILE}"
 "$SED" -r -i -e "s/gitVersion\s+string = \"[^\"]*\"/gitVersion string = \"$NEW_VERSION-dev\"/" "${VERSION_FILE}"
 gofmt -s -w "${VERSION_FILE}"
 
 echo "+++ Committing version change"
 git add "${VERSION_FILE}"
 git commit -m "Kubernetes version ${NEW_VERSION}-dev"
+
+if [[ "${VERSION_PATCH}" == "0" ]]; then
+  echo "+++ Creating release branch"
+  git branch "${release_branch}"
+fi
+
+echo "Success you must now:"
+echo ""
+echo "- Push the tag:"
+echo "   git push git@github.com:GoogleCloudPlatform/kubernetes.git v${VERSION_MAJOR}.${VERSION_MINOR}.${VERSION_PATCH}"
+if [[ "${VERSION_PATCH}" == "0" ]]; then
+  echo "- Submit HEAD as a PR to master"
+  echo "- Merge that PR"
+  echo "- Push the new release branch"
+  echo "   git push git@github.com:GoogleCloudPlatform/kubernetes.git ${release_branch}"
+else
+  echo "- Submit HEAD as a PR to ${release_branch}"
+  echo "- Merge that PR"
+fi