Unbind task item checkbox events and then rebind them

Fixes #1340

app/assets/javascripts/issue.js.coffee

@@ -9,12 +9,8 @@ class @Issue
     if $("a.btn-close").length
       $("li.task-list-item input:checkbox").prop("disabled", false)
 
-    $(".task-list-item input:checkbox").on(
-      "click"
-      null
-      "issue"
-      updateTaskState
-    )
+    $('.task-list-item input:checkbox').off('change')
+    $('.task-list-item input:checkbox').change('issue', updateTaskState)
 
     $('.issue-details').waitForImages ->
       $('.issuable-affix').affix offset:

app/assets/javascripts/merge_request.js.coffee

@@ -81,12 +81,8 @@ class @MergeRequest
       this.$('.remove_source_branch_in_progress').hide()
       this.$('.remove_source_branch_widget.failed').show()
 
-    $(".task-list-item input:checkbox").on(
-      "click"
-      null
-      "merge_request"
-      updateTaskState
-    )
+    $('.task-list-item input:checkbox').off('change')
+    $('.task-list-item input:checkbox').change('merge_request', updateTaskState)
 
   activateTab: (action) ->
     this.$('.merge-request-tabs li').removeClass 'active'