> The value of buffer-undo-list is:
 >
 > (nil
 >  (10 . 21)
 >  (1 . 21)
 >  (t 0 . 0))

The (1 . 21) entry is silly and obviously breaks undoing the prior
(insert "Foo: bar\n").  Although EQ (XCAR (tem), lbeg) was not very
intelligent, setting this to (XCAR (tem) == lbeg) doesn't seem to help
either.  Please try again with the attached patch.

GDB doesn't work here currently, so I can't debug this.  But could you
try finding out in `insert-file-contents' (1) why the test in

	      if (CONSP (tem) && INTEGERP (XCAR (tem)) &&
		  INTEGERP (XCDR (tem)) && (XCAR (tem) == lbeg))
		/* In the non-visiting case record only the final insertion. */
		current_buffer->undo_list =
		  Fcons (Fcons (lbeg, lend), Fcdr (old_undo));

fails and (2) which value old_undo has here?  Thanks in advance.