fix ambigious column on many to many with select load

Author: taylorotwell

Diff for: src/Illuminate/Database/Eloquent/Builder.php

@@ -7,6 +7,7 @@
 use Exception;
 use Illuminate\Contracts\Support\Arrayable;
 use Illuminate\Database\Concerns\BuildsQueries;
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
 use Illuminate\Database\Eloquent\Relations\Relation;
 use Illuminate\Database\Query\Builder as QueryBuilder;
 use Illuminate\Pagination\Paginator;
@@ -1143,7 +1144,11 @@ protected function parseWithRelations(array $relations)
     protected function createSelectWithConstraint($name)
     {
         return [explode(':', $name)[0], static function ($query) use ($name) {
-            $query->select(explode(',', explode(':', $name)[1]));
+            $query->select(array_map(static function ($column) use ($query) {
+                return $query instanceof BelongsToMany
+                        ? $query->getRelated()->getTable().'.'.$column
+                        : $column;
+            }, explode(',', explode(':', $name)[1])));
         }];
     }