If you put the following line in Modules/Setup:

  SELF=$(SELF)

and then type "make", sysconfig.py's parse_makefile
function gets into an infinite loop.  Attached is a
backtrace after typing Control-C during the infinite loop.

Here is the (honest?) mistake that I made in Setup that
triggered this (Notice the extra "\"):

PURE_STUBLIBS=-lpurify_stubs -lquantify_stubs \
	-L/foo/lib \
	-R/foo/lib \
pure puremodule.c $(WHICH_PURE_PRODUCTS) $(PURE_INCLS)
$(PURE_STUBLIBS)