Prefer if over return

app/models/project.rb

@@ -431,14 +431,18 @@ class Project < ActiveRecord::Base
 
   def builds_for(build_name, ref = 'HEAD')
     ct = commit(ref)
-    return builds.none unless ct
 
-    sha = commit(ref).sha
+    if ct.nil?
+      builds.none
+
+    else
+      sha = ct.sha
 
       builds.joins(:pipeline).
         merge(Ci::Pipeline.where(sha: sha)).
         where(name: build_name)
     end
+  end
 
   def merge_base_commit(first_commit_id, second_commit_id)
     sha = repository.merge_base(first_commit_id, second_commit_id)