I am sure you are mistaken.

The reason I'm sure is that I just tried it:

  entities = data.MyModel.all().fetch(1010)
  print len(entities) # Prints 1010

Then I thought that perhaps you meant the limitation still exists in the low-level datastore API — and it's worked around by the Model interface making multiple calls to the low-level API — but that's not true either:

  from google.appengine.api import datastore
  entities = datastore.Query("MyModel").Get(1010)
  print len(entities) # Still prints 1010

So: what do you mean?