18.104.22.168: two regressions from the 1.0.28. series
* from 22.214.171.124: when destructuring a constant :INITIAL-CONTENTS to
MAKE-ARRAY, take care to quote the elements.
* from 126.96.36.199: handle :BACK and :UP in CANONICALIZE-PATHNAME, and
make sure they do not appear after :WILD-INFERIORS or :ABSOLUTE.
I'm more and more concinved that MAKE-PATHNAME should canonicalize,
though, so that these checks don't need to be carried out by users
of pathnames -- but leaving that for later.
...how appropriate that it is .71 that fixes both.