Fix check for existence of new branch button (!4630)

CHANGELOG

@@ -5,6 +5,7 @@ v 8.10.0 (unreleased)
   - Wrap code blocks on Activies and Todos page. !4783 (winniehell)
   - Add Sidekiq queue duration to transaction metrics.
   - Make images fit to the size of the viewport !4810
+  - Fix check for New Branch button on Issue page !4630 (winniehell)
   - Fix MR-auto-close text added to description. !4836
   - Fix pagination when sorting by columns with lots of ties (like priority)
   - Exclude email check from the standard health check

app/assets/javascripts/issue.js.coffee

@@ -99,7 +99,7 @@ class @Issue
 
     # If the user doesn't have the required permissions the container isn't
     # rendered at all.
-    return unless $container
+    return if $container.length is 0
 
     $.getJSON($container.data('path'))
       .error ->