Take extra care in handling PREV in case the symlink has gone bad.

TODO

@@ -2,10 +2,6 @@ What about themes? Templates are themes. DUH.
 Plugins? Injection support for HEAD and BODY. What about predicate-based injection?
 
 BUGS:
-; Generated directories aren't being removed properly.
-; Post-receive hook on server doesn't appear to be executing. Invoking manually behaves as expected. What's going on here?
-;; Suspect these issues are related. read-symlink doesn't return a directory pathname which causes cl-fad:delete-directory-and-files to blowup. Maybe stop using iolib for symlinks? What is portable?
-;;; Propose replacing iolib based symlink code with something that uses DIRECTORY and/or TRUENAME.
 ; Slugs aren't unicode safe. See [reddit discussion](http://www.reddit.com/r/lisp/comments/yvh6g/coleslaw_jekylllike_static_blogware_in_500_lines/) and [mozilla code](https://github.com/mozilla/unicode-slugify/blob/master/slugify/__init__.py).
 
 TODO:

src/coleslaw.lisp

@@ -52,7 +52,8 @@ If RAW is non-nil, write the content without wrapping it in the base template."
         (ensure-directories-exist new-build)
         (with-current-directory coleslaw-conf:*basedir*
           (run-program "mv" (mapcar #'namestring (list staging new-build)))
-          (when (probe-file prev)
+          (if (and (probe-file prev) (equal prev (truename prev)))
+              (delete-file prev)
               (cl-fad:delete-directory-and-files (truename prev)))
           (when (probe-file curr)
             (update-symlink prev (truename curr)))