Marc:
I forgot to do a "make bootstrap" before doing a "make update" so the "make" failed because gsc-comp was not found to compile _io.scm.
So I just copied gsc/gsc to gsc-comp and did another "make update".
But this second time, it assumed the previous "make" worked, and did an hg update before doing the next "make", and everything bombed.
So I suggest that "make update" do a "make" just after the "hg pull"; then if "make update" fails, and you can fix it by hand, you can just do another "make update" to get things rolling again.
Brad