Add transaction check to SQLite2 adapter to fix test_sqlite_add_colum…

…n_in_transaction_raises_statement_invalid [rails#1669 state:resolved]

Signed-off-by: Pratik Naik <pratiknaik@gmail.com>

activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb

@@ -402,6 +402,10 @@ def rename_table(name, new_name)
       end
 
       def add_column(table_name, column_name, type, options = {}) #:nodoc:
+        if @connection.respond_to?(:transaction_active?) && @connection.transaction_active?
+          raise StatementInvalid, 'Cannot add columns to a SQLite database while inside a transaction'
+        end
+
         alter_table(table_name) do |definition|
           definition.column(column_name, type, options)
         end