In my case, what happened was after I fixed the untangle guile script, I needed to delete the (now empty) f_print.c. The build rules for those files need to be tweaked; in general, when you use redirection to create a file you should use a temp file, so that the file doesn't exist if the command failed.
i.e. this is bad:
a : b
foo < a > b
this is good:
a : b
foo < a > b.tmp
mv b.tmp b
if "foo" fails, make won't run the "mv b.tmp b" step, and thus b won't
be updated.
