Make SelectMultipleField's tests more robust.
Make SelectMultipleField's tests more robust.

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