[rubygems/rubygems] Roll back to Dir.chdir block

since without that, evaluating the gemspec from
outside `File.expand_path( __dir__)` won't work.

Signed-off-by: Utkarsh Gupta <utkarsh@debian.org>

https://github.com/rubygems/rubygems/commit/9e5e52a1d9

lib/bundler/templates/newgem/newgem.gemspec.tt

@@ -24,7 +24,9 @@ Gem::Specification.new do |spec|
 
   # Specify which files should be added to the gem when it is released.
   # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
-  spec.files         = `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
+  spec.files = Dir.chdir(File.expand_path(__dir__)) 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"]