Bundler 2 is shipped with truffleruby-head now

https://www.ruby-lang.org/en/news/2020/04/05/support-of-ruby-2-4-has-ended/

README.md

@@ -29,9 +29,8 @@ Only versions published by [RubyInstaller](https://rubyinstaller.org/downloads/a
 Due to that, Ruby 2.2 resolves to 2.2.6 on Windows and 2.2.10 on other platforms.
 And Ruby 2.3 on Windows only has builds for 2.3.0, 2.3.1 and 2.3.3.
 
-Note that Ruby ≤ 2.3 and the OpenSSL version it needs (1.0.2) are both end-of-life,
-which means Ruby ≤ 2.3 is unmaintained and considered insecure.
-On Windows, Ruby 2.4 uses OpenSSL 1.0.2, which is no longer maintained.
+Note that Ruby ≤ 2.4 and the OpenSSL version it needs (1.0.2) are both end-of-life,
+which means Ruby ≤ 2.4 is unmaintained and considered insecure.
 
 ### Supported Platforms
 
@@ -204,6 +203,9 @@ if the [virtual environment](https://github.com/actions/virtual-environments) is
 * Make sure to use the same operating system and version.
 * Make sure to use the same version of libssl.
 * Make sure that the operating system has `libyaml-0` installed
+* The environment variable `RUNNER_TOOL_CACHE` must be set to same value as on GitHub-hosted runners
+  (`/opt/hostedtoolcache` on Linux, `/Users/runner/hostedtoolcache` on macOS, `C:\hostedtoolcache\windows` on Windows).
+* That directory must be writable by the `runner` user.
 * The runner software is running as user `runner` with a home directory of `/home/runner`, or you have created a symlink for the home directory of whatever user that the runner is running as to `/home/runner`.
 
 In other cases, please use a system Ruby or [install Ruby manually](https://github.com/postmodern/chruby/wiki#installing-rubies) instead.

dist/index.js

@@ -51181,7 +51181,7 @@ async function setupRuby(options = {}) {
   const [engine, parsedVersion] = parseRubyEngineAndVersion(inputs['ruby-version'])
 
   let installer
-  if (platform === 'windows-latest' && engine === 'ruby') {
+  if (platform.startsWith('windows-') && engine === 'ruby') {
     installer = __webpack_require__(216)
   } else {
     installer = __webpack_require__(974)
@@ -51365,9 +51365,9 @@ async function installBundler(bundlerVersionInput, lockFile, platform, rubyPrefi
     bundlerVersion = '1'
   }
 
-  if (engine === 'ruby' && common.isHeadVersion(rubyVersion) && bundlerVersion === '2') {
+  if ((engine === 'ruby' || engine === 'truffleruby') && common.isHeadVersion(rubyVersion) && bundlerVersion === '2') {
     console.log(`Using Bundler 2 shipped with ${engine}-${rubyVersion}`)
-  } else if (engine === 'truffleruby' && bundlerVersion === '1') {
+  } else if (engine === 'truffleruby' && !common.isHeadVersion(rubyVersion) && bundlerVersion === '1') {
     console.log(`Using Bundler 1 shipped with ${engine}`)
   } else {
     const gem = path.join(rubyPrefix, 'bin', 'gem')

index.js

@@ -39,7 +39,7 @@ export async function setupRuby(options = {}) {
   const [engine, parsedVersion] = parseRubyEngineAndVersion(inputs['ruby-version'])
 
   let installer
-  if (platform === 'windows-latest' && engine === 'ruby') {
+  if (platform.startsWith('windows-') && engine === 'ruby') {
     installer = require('./windows')
   } else {
     installer = require('./ruby-builder')
@@ -223,9 +223,9 @@ async function installBundler(bundlerVersionInput, lockFile, platform, rubyPrefi
     bundlerVersion = '1'
   }
 
-  if (engine === 'ruby' && common.isHeadVersion(rubyVersion) && bundlerVersion === '2') {
+  if ((engine === 'ruby' || engine === 'truffleruby') && common.isHeadVersion(rubyVersion) && bundlerVersion === '2') {
     console.log(`Using Bundler 2 shipped with ${engine}-${rubyVersion}`)
-  } else if (engine === 'truffleruby' && bundlerVersion === '1') {
+  } else if (engine === 'truffleruby' && !common.isHeadVersion(rubyVersion) && bundlerVersion === '1') {
     console.log(`Using Bundler 1 shipped with ${engine}`)
   } else {
     const gem = path.join(rubyPrefix, 'bin', 'gem')