Let t.foreign_key use the same `to_table` twice

Previously if you used `t.foreign_key` twice within the same
`create_table` block using the same `to_table`, all statements except
the final one would fail silently. For example, the following code:

    def change
      create_table :flights do |t|
        t.integer :from_id, index: true, null: false
        t.integer :to_id,   index: true, null: false

        t.foreign_key :airports, column: :from_id
        t.foreign_key :airports, column: :to_id
      end
    end

Would only create one foreign key, on the column `from_id`.

This commit allows multiple foreign keys to the same table to be created
within one `create_table` block.

1 files changed, 2 insertions, 2 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
index cb10ca9929..4f97c7c065 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
@@ -212,7 +212,7 @@ module ActiveRecord
       def initialize(name, temporary, options, as = nil)
         @columns_hash = {}
         @indexes = {}
-        @foreign_keys = {}
+        @foreign_keys = []
         @primary_keys = nil
         @temporary = temporary
         @options = options
@@ -330,7 +330,7 @@ module ActiveRecord
       end
 
       def foreign_key(table_name, options = {}) # :nodoc:
-        foreign_keys[table_name] = options
+        foreign_keys.push([table_name, options])
       end
 
       # Appends <tt>:datetime</tt> columns <tt>:created_at</tt> and