empty files are lost when you press [test] about web

[JonJagger]

Fixed. The problem was the file utility. It reports empty files as binary files.
See cyber-dojo-tools/image_builder@5ddf46b

Which added these lines inside a [for filename do] so we know ${filename} exists

if [ ! -s ${filename} ]; then
    # handle empty files which file reports are binary
    echo ${filename} >> ${TAR_LIST}
fi

Note that

[ -s ${filename} ] 

means filename has size greater than zero. So the ! negates this which means it has size zero.

[JonJagger]

This problem is back. No it's not back! The problem was an out of date image for ruby-approval. Viz, an image for ruby-approval that had not been rebuilt since the [ -s ${filename} } fix documented in the previous comment.