fix issue cloning url (#1702)

Author: cifarquhar

common-theme/layouts/partials/block/backlog-issue.html

@@ -2,7 +2,7 @@
     <summary class="c-issue__title e-heading__3">
         {{ .block.name }}
         <a class="c-issue__link" href="{{ .block.src }}">🔗</a>
-        <a href="https://curriculum.codeyourfuture.io/api/clone?state={{ dict " issue" .number "module" .repo "sprint"
+        <a href="https://curriculum.codeyourfuture.io/api/clone?state={{ dict "issue" .block.number "module" .repo "sprint"
             .sprint "prevURL" (urls.AbsLangURL .path) | jsonify }}" class="e-button"
             data-props="{{ .Page.RelPermalink }}">
             Clone