fixed issue 1587:Mongodb error on id

VERSION

@@ -1 +1 @@
-Version 2.6.0-development+timestamp.2013.07.16.13.14.21
+Version 2.6.0-development+timestamp.2013.07.17.07.36.50

gluon/dal.py

@@ -5540,8 +5540,9 @@ class MongoDBAdapter(NoSQLAdapter):
         filter = None
         if query:
             filter = self.expand(query)
+        # do not try to update id fields to avoid backend errors
         modify = {'$set': dict((k.name, self.represent(v, k.type)) for
-                  k, v in fields)}
+                  k, v in fields if (not k.name in ("_id", "id")))}
         return modify, filter
 
     def update(self, tablename, query, fields, safe=None):

gluon/utils.py

@@ -80,7 +80,7 @@ def compare(a, b):
 
 def md5_hash(text):
     """ Generate a md5 hash with the given text """
-    return md5(text).hexdigest()
+    return md5.new(text).hexdigest()
 
 
 def simple_hash(text, key='', salt='', digest_alg='md5'):