strange message using delete-intermediate-files with -dbackend=eps

[Mark Polesky]

In 2.11.60, running a file like this...

   lilypond -dbackend=eps -ddelete-intermediate-files=#t my_file.ly

...generates the following message:

Layout output to `my_file-1.eps'...
Converting to `./my_file-1.pdf'...
Layout output to `my_file.eps'...
Converting to `./my_file.pdf'...
C:/LilyPond/usr/share/lilypond/current/scm/backend-library.scm:149:21:
  In procedure delete-file in expression
    (delete-file (string-append base "." ...)):
      C:/LilyPond/usr/share/lilypond/current/scm/backend-library.scm:149:21:
        No such file or directory

To be clear, this behavior is not new to 2.11.60.

I discovered this while running my_file.ly with --png, like so:

   lilypond -dbackend=eps -dno-gs-load-fonts -dinclude-eps-fonts
   -ddelete-intermediate-files=#t --png my_file.ly

I initially thought it was related to --png, but it's not. This compiles
without generating the above message:

   lilypond -ddelete-intermediate-files=#t --png my_file.ly

Although of course the fonts won't be there.

Curious to know what's going on, and as always, happy to help!
- Mark