Good catch Michael, thank you, I had completely forgotten about Windows.  I've updated the patch.

Cheers,
Colin

On Thu, 10 Jun 2021, at 00:46, Michael Albinus wrote:
"Colin Woodbury" <colin@fosskers.ca> writes:

> Hi all,

Hi Colin,

> +          ((equal ?/ (string-to-char (substring file -1))) (error "Filename is a directory: %s" filename))

This shall be (directory-name-p file) . You cannot assume that ?/ is
always the directory separator, for example on MS Windows.

Best regards, Michael.