Fix `JoinDependency` with using a custom table

Without this fix, `JoinDependency` doesn't use a custom table alias:

```
% ARCONN=sqlite3 be ruby -w -Itest test/cases/relations_test.rb -n test_using_a_custom_table_with_joins_affects_the_wheres
Using sqlite3
Run options: -n test_using_a_custom_table_with_joins_affects_the_wheres --seed 14531

E

Error:RelationTest#test_using_a_custom_table_with_joins_affects_the_wheres:
ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column: posts.author_id: SELECT  "omg_posts".* FROM "posts" "omg_posts" INNER JOIN "authors" ON "authors"."id" = "posts"."author_id" WHERE "omg_posts"."title" = ? LIMIT ?
```

1 files changed, 14 insertions, 5 deletions

diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index 82e1077e87..316ea75e36 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -1785,15 +1785,15 @@ class RelationTest < ActiveRecord::TestCase
   end
 
   test "using a custom table affects the wheres" do
-    table_alias = Post.arel_table.alias("omg_posts")
+    post = posts(:welcome)
 
-    table_metadata = ActiveRecord::TableMetadata.new(Post, table_alias)
-    predicate_builder = ActiveRecord::PredicateBuilder.new(table_metadata)
-    relation = ActiveRecord::Relation.create(Post, table_alias, predicate_builder)
+    assert_equal post, custom_post_relation.where!(title: post.title).take
+  end
 
+  test "using a custom table with joins affects the joins" do
     post = posts(:welcome)
 
-    assert_equal post, relation.where!(title: post.title).take
+    assert_equal post, custom_post_relation.joins(:author).where!(title: post.title).take
   end
 
   test "#load" do
@@ -1950,4 +1950,13 @@ class RelationTest < ActiveRecord::TestCase
       end
     end
   end
+
+  private
+    def custom_post_relation
+      table_alias = Post.arel_table.alias("omg_posts")
+      table_metadata = ActiveRecord::TableMetadata.new(Post, table_alias)
+      predicate_builder = ActiveRecord::PredicateBuilder.new(table_metadata)
+
+      ActiveRecord::Relation.create(Post, table_alias, predicate_builder)
+    end
 end