Fix Create new branch (#11294)

Fix #11212

Signed-off-by: Andrew Thornton <art27@cantab.net>

web_src/js/index.js

@@ -3085,7 +3085,7 @@ function initFilterBranchTagDropdown(selector) {
           if (!this.showCreateNewBranch) {
             return;
           }
-          this.$refs.newBranchForm.trigger('submit');
+          $(this.$refs.newBranchForm).trigger('submit');
         },
         focusSearchField() {
           const vm = this;