Use git ls-files for bundled gems preparation

irb.gemspec

@@ -21,19 +21,9 @@ Gem::Specification.new do |spec|
   spec.metadata["documentation_uri"] = "https://ruby.github.io/irb/"
   spec.metadata["changelog_uri"] = "#{spec.homepage}/releases"
 
-  spec.files         = [
-    "Gemfile",
-    "LICENSE.txt",
-    "README.md",
-    "Rakefile",
-    "bin/console",
-    "bin/setup",
-    "doc/irb/irb-tools.rd.ja",
-    "doc/irb/irb.rd.ja",
-    "exe/irb",
-    "irb.gemspec",
-    "man/irb.1",
-  ] + Dir.glob("lib/**/*")
+  spec.files         = Dir.chdir(File.expand_path('..', __FILE__)) do
+    `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
+  end
   spec.bindir        = "exe"
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]