Fixed infinite loop when environment is missing in database.yml

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@35 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -83,7 +83,11 @@ def self.establish_connection(spec = nil)
         when ConnectionSpecification
           @@defined_connections[self] = spec
         when Symbol, String
-          establish_connection(configurations[spec.to_s])
+          if configuration = configurations[spec.to_s]
+            establish_connection(configuration)
+          else
+            raise AdapterNotSpecified
+          end
         else
           spec = symbolize_strings_in_hash(spec)
           unless spec.key?(:adapter) then raise AdapterNotSpecified end