Now I am running it on a latest GIT tree this way:
$ tools/winapi/msvcmaker --no-wine .: searching for /^Makefile.in$/
And after a while it appends this string to the end of last line:
readline() on closed filehandle IN at tools/winapi/msvcmaker line 134.
Maybe it doesn't indicate any harm, but in ideal world this should be fixed. I don't know perl, unfortunately.