[rubygems/rubygems] Delete partial file and re-raise on Errno::ENOSPC.

Add test for not leaving empty files if ENOSPC is raised during 'gem install'

https://github.com/rubygems/rubygems/commit/8e0e20f079

lib/rubygems.rb

@@ -774,6 +774,10 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
     open_file(path, "wb") do |io|
       io.write data
     end
+  rescue Errno::ENOSPC
+    # If we ran out of space but the file exists, it's *guaranteed* to be corrupted.
+    File.delete(path) if File.exist?(path)
+    raise
   end
 
   ##

test/rubygems/test_gem_installer.rb

@@ -2222,6 +2222,37 @@ gem 'other', version
     assert_equal @spec, eval(File.read(@spec.spec_file))
   end
 
+  def test_leaves_no_empty_cached_spec_when_no_more_disk_space
+    @spec = setup_base_spec
+    FileUtils.rm @spec.spec_file
+    assert_path_not_exist @spec.spec_file
+
+    @spec.files = %w[a.rb b.rb c.rb]
+
+    installer = Gem::Installer.for_spec @spec
+    installer.gem_home = @gemhome
+
+    File.class_eval do
+      alias_method :original_write, :write
+
+      def write(data)
+        raise Errno::ENOSPC
+      end
+    end
+
+    assert_raise Errno::ENOSPC do
+      installer.write_spec
+    end
+
+    assert_path_not_exist @spec.spec_file
+  ensure
+    File.class_eval do
+      remove_method :write
+      alias_method :write, :original_write # rubocop:disable Lint/DuplicateMethods
+      remove_method :original_write
+    end
+  end
+
   def test_dir
     installer = setup_base_installer