Dear Maintainer,

I have found this bug while writing autopkgtests for the package in Ubuntu. By default, `shtool echo` should not expand escape sequences.
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Steps to reproduce
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1. apt install shtool on Ubuntu Stonking
2. Run the following command:

   ubuntu@s:~$ shtool echo '\1' | cat -v
   ^A

3. Observe the output with the unprintable character instead of the literal '\1' line.

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Expected output
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   ubuntu@s:~$ shtool echo '\1' | cat -v
   \1

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Notes
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This behavior is required by the currently failing first upstream test:

@begin{echo}
test ".`shtool echo foo bar quux`" = ".foo bar quux"
bytes=`shtool echo -n foo | wc -c | awk '{ printf("%s", $1); }'`
test ".$bytes" = .3
bytes=`shtool echo '\1' | wc -c | awk '{ printf("%s", $1); }'`
test ".$bytes" = .3
@end{echo}

The upstream test consistently fails but still exits with zero. In
Ubuntu, we have a patch to use non-zero exit code on failure, and
another patch to skip the test case until a solution is decided.

LP Bug:
https://bugs.launchpad.net/ubuntu/+source/shtool/+bug/2167073