after fiddling around with the PATH for a few hours and stumbling over
http://blog.gmane.org/gmane.comp.gnu.make.windows/month=20100501 i actually realised, that the error is produced by the sh.exe in an
installation of AVR Studie 4 i have on my PC. Deleting the relevant part
of the PATH or renaming the sh.exe to anything else solves the problem.
Now i do not know if the problem actually lies in the mingw32-make or the
sh.exe, just wanted you to know of the incompatability.