Commit a22d7821cb ensured that a nested pseudo-terminal device is
only created for the process running inside the container, if the Toolbx
binary's standard input and output streams are connected to a terminal.
Therefore, 'echo ...' no longer ends with an unwanted extra carriage
return when terminal devices are absent - there's only a line feed for
the trailing newline. Hence, there's no need to use the -n flag to skip
the trailing newline.
This reverts parts of commit 16b0c5d88f.
https://github.com/containers/toolbox/issues/157
f779c798f0