reordered predicates, added comments

routes/v1.js

@@ -97,12 +97,14 @@ function addRoutes(app, peliasConfig) {
   const placeholderService = serviceWrapper(placeholderConfiguration);
   const isPlaceholderServiceEnabled = _.constant(placeholderConfiguration.isEnabled());
 
+  // use coarse reverse when requested layers are all coarse
   const coarse_reverse_should_execute = all(
-    not(hasRequestErrors), isPipServiceEnabled, isCoarseReverse
+    isPipServiceEnabled, isCoarseReverse, not(hasRequestErrors)
   );
 
+  // fallback to coarse reverse when regular reverse didn't return anything
   const coarse_reverse_fallback_should_execute = all(
-    isPipServiceEnabled, not(hasRequestErrors), not(hasResponseData), not(isCoarseReverse)
+    isPipServiceEnabled, not(isCoarseReverse), not(hasRequestErrors), not(hasResponseData)
   );
 
   const placeholderShouldExecute = all(