Rename default branch from master to main

app/functions.php

@@ -197,12 +197,12 @@ function build_app_version($ref, $commit_hash)
     }
 
     if ($commit_hash !== '$Format:%H$') {
-        return 'master.'.$commit_hash;
+        return 'main.'.$commit_hash;
     } else if (file_exists('/version.txt')) {
         return rtrim(file_get_contents('/version.txt'));
     }
 
-    return 'master.unknown_revision';
+    return 'main.unknown_revision';
 }
 
 /**