use complete path in `preheat-cache`

pollen/private/preheat-cache.rkt

@@ -32,7 +32,7 @@
                                                     pagetree-source?))])
                         (proc path))
                #:unless (path-cached? path))
-      path))
+      (path->complete-path path)))
 
   (cond
     [(null? uncached-paths)

pollen/private/ts.rktd

@@ -1 +1 @@
-1561689870
+1562556705