fix(script): follow redirected URL of github latest release

When checking version and desired version is not set, we follow
redirected URL of github latest release to get the latest tag instead of
trying to get the tag value from html content.

Closes #5480

Signed-off-by: Arief Hidayat <mr.arief.hidayat@gmail.com>

scripts/get

@@ -78,16 +78,31 @@ verifySupported() {
 # checkDesiredVersion checks if the desired version is available.
 checkDesiredVersion() {
   # Use the GitHub releases webpage for the project to find the desired version for this project.
-  local release_url="https://github.com/helm/helm/releases/${DESIRED_VERSION:-latest}"
+  local latest_release_url="https://github.com/helm/helm/releases/latest"
+  local release_url
+  if [ "x$DESIRED_VERSION" == "x" ]; then
+    if type "curl" > /dev/null; then
+      release_url=$(curl -Ls -o /dev/null -w %{url_effective} $latest_release_url)
+    elif type "wget" > /dev/null; then
+      release_url=$(wget $latest_release_url --server-response -O /dev/null 2>&1 | awk '/^  Location: /{DEST=$2} END{ print DEST}')
+    fi
+  else
+    release_url="https://github.com/helm/helm/releases/${DESIRED_VERSION}"
+  fi
+
+  local status_code
   if type "curl" > /dev/null; then
-    TAG=$(curl -SsL $release_url | awk '/\/tag\//' | grep -v no-underline | grep "<a href=\"/helm/helm/releases" | head -n 1 | cut -d '"' -f 2 | awk '{n=split($NF,a,"/");print a[n]}' | awk 'a !~ $0{print}; {a=$0}')
+    status_code=$(curl --write-out %{http_code} --silent --output /dev/null $release_url)
   elif type "wget" > /dev/null; then
-    TAG=$(wget -q -O - $release_url | awk '/\/tag\//' | grep -v no-underline | grep "<a href=\"/helm/helm/releases" | head -n 1 | cut -d '"' -f 2 | awk '{n=split($NF,a,"/");print a[n]}' | awk 'a !~ $0{print}; {a=$0}')
+    status_code=$(wget --spider -S $release_url -O /dev/null 2>&1 | grep "HTTP/" | awk '{print $2}')
   fi
-  if [ "x$TAG" == "x" ]; then
+  
+  if [[ "$status_code" -ne 200 ]] ; then
     echo "Cannot determine ${DESIRED_VERSION} tag."
     exit 1
   fi
+  
+  TAG=$(echo $release_url | grep -oE "[^/]+$" )
 }
 
 # checkHelmInstalledVersion checks which version of helm is installed and