[fix] 302 redirects

Add new function `app:redirect-to#1 to replace response:redirect-to#1 until
eXist-db/exist#4249 is fixed.

modules/app.xqm

@@ -211,7 +211,7 @@ declare function app:view-package($node as node(), $model as map(*), $mode as xs
                             ()
                     )
                 return
-                    response:redirect-to(xs:anyURI($info-url))
+                    app:redirect-to($info-url)
             (: view current package info :)
             else
                 let $packages := $package-group//package
@@ -441,3 +441,12 @@ declare function app:requires-to-english($requires as element()) {
     else
         " version " || $config:default-exist-version
 };
+
+(:~
+ : helper function to work around a bug in response:redirect-to#1
+ : see https://github.com/eXist-db/exist/issues/4249
+ :)
+declare function app:redirect-to ($location as xs:string) {
+    response:set-status-code(302),
+    response:set-header("Location", $location)
+};

modules/find.xq

@@ -43,14 +43,10 @@ return
                     $newest-compatible-package/version ! attribute version {.},
                     $newest-compatible-package/@path
                 }
-            else if ($zip) then (
-                response:set-status-code(302),
-                response:set-header("Location", $abs-public || $xar-filename || ".zip")
-            )
-            else (
-                response:set-status-code(302),
-                response:set-header("Location", $abs-public || $xar-filename)
-            )
+            else if ($zip) then
+                app:redirect-to($abs-public || $xar-filename || ".zip")
+            else
+                app:redirect-to($abs-public || $xar-filename)
     else 
         (
             response:set-status-code(404),