Remove BUNDLED WITH earlier

Because Ruby 2.6.5 ships with Bundler 2 it also includes a check for bundler version and will error if the version does not match. This commit bumps up the logic of when the BUNDLED WITH lines in the Gemfile.lock get removed so they allow the Buildpack to execute correctly.

lib/language_pack/helpers/bundler_wrapper.rb

@@ -165,6 +165,10 @@ def lockfile_parser
   def fetch_bundler
     instrument 'fetch_bundler' do
       return true if Dir.exists?(bundler_path)
+
+      topic("Installing bundler #{@version}")
+      bundler_version_escape_valve!
+
       FileUtils.mkdir_p(bundler_path)
       Dir.chdir(bundler_path) do
         @fetcher.fetch_untar(@bundler_tar)
@@ -202,4 +206,12 @@ def detect_bundler_version_and_dir_name!
       raise UnsupportedBundlerVersion.new(BLESSED_BUNDLER_VERSIONS, major)
     end
   end
+
+  def bundler_version_escape_valve!
+    topic("Removing BUNDLED WITH version in the Gemfile.lock")
+    contents = File.read("Gemfile.lock")
+    File.open("Gemfile.lock", "w") do |f|
+      f.write contents.sub(/^BUNDLED WITH$(\r?\n)   (?<major>\d+)\.\d+\.\d+/m, '')
+    end
+  end
 end

lib/language_pack/ruby.rb

@@ -783,12 +783,6 @@ def write_bundler_shim(path)
   # runs bundler to install the dependencies
   def build_bundler(default_bundle_without)
     instrument 'ruby.build_bundler' do
-      topic("Removing BUNDLED WITH version in the Gemfile.lock")
-      contents = File.read("Gemfile.lock")
-      File.open("Gemfile.lock", "w") do |f|
-        f.write contents.sub(/^BUNDLED WITH$(\r?\n)   (?<major>\d+)\.\d+\.\d+/m, '')
-      end
-
       log("bundle") do
         bundle_without = env("BUNDLE_WITHOUT") || default_bundle_without
         bundle_bin     = "bundle"