Adding new field removes "number" Data Type value

[benkeen]

To reproduce:

• create a field and set to "number"
• add some data and set the values to something like 1, 10, 2 and see that sorting sorts numerically (1,2, 10).
• add a new field
• return to the results page and sort again, see that it now sorts by 1, 10, 2.