grass.to.ipw

Have any of you had any experience with the
contributed program grass.to.ipw? The program
is supposed to write out a raster map in ipw
format. When I run the version in 4.1, I get
the error:

grass.to.ipw: BUG:
    called with NULL string to be duplicated
    (file "hstrdup.c", line 74)
    (command line: grass.to.ipw)

Any clues?

Bob Harrington
Hydrology and Water Resources
University of Arizona
bobh@hwr.arizona.edu