Revert regression introduced in 81eac415ad03d93596a0d8da92bdccd9ecd4ee63, which caused 'docker run -i' to never close stdin

Upstream-commit: a6779bcae2df4805b8024c56f81ee3afac46ff93
Component: engine

components/engine/commands.go

@@ -927,6 +927,7 @@ func (srv *Server) CmdRun(stdin io.ReadCloser, stdout io.Writer, args ...string)
 		if !config.Detach {
 			Go(func() error {
 				_, err := io.Copy(cmdStdin, stdin)
+				cmdStdin.Close()
 				return err
 			})
 		}