Fix a few appengine tests using _default.
Fix a few appengine tests using _default.

hsum/wtforms,pawl/wtforms,wtforms/wtforms,Aaron1992/wtforms,Xender/wtforms,subyraman/wtforms,Aaron1992/wtforms,pawl/wtforms,jmagnusson/wtforms,skytreader/wtforms,cklein/wtforms,crast/wtforms