Auto merge of #2066 - rubygems:workaround-git-ls-files, r=hsbt

Workaround for non-git environment.

Fixes #2064

Ignored `git` command. It's no effects for installation of vendored bundler.

Because we overwrite file list when invoking `update_rubygems`.

Author: bundlerbot

lib/rubygems/commands/setup_command.rb

@@ -356,6 +356,10 @@ def install_default_bundler_gem
 
     mkdir_p Gem::Specification.default_specifications_dir
 
+    # Workaround for non-git environment.
+    gemspec = File.read('bundler/bundler.gemspec').gsub(/`git ls-files -z`/, "''")
+    File.open('bundler/bundler.gemspec', 'w'){|f| f.write gemspec }
+
     bundler_spec = Gem::Specification.load("bundler/bundler.gemspec")
     bundler_spec.files = Dir.chdir("bundler") { Dir["{*.md,{lib,exe,man}/**/*}"] }
     bundler_spec.executables -= %w[bundler bundle_ruby]