Log file error message - file not normalised

[Peter Gentry]

I have after some research discovered the difference between ly:message and 
(display...) and even referred to an include file
include ".\ranges\enharmonic.ly". (as in recent message to lilypond.user)

[Frescobaldi 2.0.16 Lily 2.18.2 OS Vista]

I can provide debug information to the log file but although everything works 
fine the log 
file starts with the error message 

Parsing...
Programming error: file name not normalized: .\ranges\enharmonic.ly
Continuing cross fingers

The file is "included" correctly. Is this just a minor glitch - nothing in the 
manuals for 2.18.2 refers.

regards
Peter Gentry