Fix archive filename matching, recent regression.

The census test didn't pass anymore because I broke the archive filename
matching in b17383fa90b81408fa08566bc131ea5b02606023, where the special
variable *csv-path-root* stoped being authoritative in the archive case.

To fix, initialize that variable to nil and give its value priority as
soon as it's non-nil, such as the archive case.

src/params.lisp

@@ -57,8 +57,8 @@
 (defparameter *state* nil
   "State of the current loading.")
 
-(defparameter *csv-path-root*
-  (merge-pathnames "csv/" (user-homedir-pathname)))
+(defparameter *csv-path-root* nil
+  "Where to load CSV files from, when loading from an archive.")
 
 (defparameter *root-dir*
   (make-pathname :directory "/tmp/pgloader/")

src/sources/sources.lisp

@@ -189,7 +189,9 @@
       (:inline   (car part))		; because of &rest
       (:stdin    *standard-input*)
       (:regex    (destructuring-bind (keep regex root) part
-		   (filter-directory regex :keep keep :root root)))
+		   (filter-directory regex
+                                     :keep keep
+                                     :root (or *csv-path-root* root))))
       (:filename (let* ((filename (first part))
                         (realname
                          (if (fad:pathname-absolute-p filename) filename