possible bug in new IS_IN_DB groupby

[mr.freeze]

I get this on an app that worked before (running trunk):

Traceback (most recent call last):
File "C:\Users\freeze\workspace\web2py\gluon\restricted.py", line
178, in restricted
exec ccode in environment
File "C:/Users/freeze/workspace/web2py/applications/widgets/
controllers/default.py", line 129, in <module>
File "C:\Users\freeze\workspace\web2py\gluon\globals.py", line 96,
in <lambda>
self._caller = lambda f: f()
File "C:/Users/freeze/workspace/web2py/applications/widgets/
controllers/default.py", line 40, in autocomplete_local
form = SQLFORM(db.things)
File "C:\Users\freeze\workspace\web2py\gluon\sqlhtml.py", line 696,
in __init__
inp = self.widgets.options.widget(field, default)
File "C:\Users\freeze\workspace\web2py\gluon\sqlhtml.py", line 187,
in widget
options = requires[0].options()
File "C:\Users\freeze\workspace\web2py\gluon\validators.py", line
394, in options
self.build_set()
File "C:\Users\freeze\workspace\web2py\gluon\validators.py", line
376, in build_set
groupby = self.groupby or reduce(lambda a,b:a|b,self.fields)
File "C:\Users\freeze\workspace\web2py\gluon\validators.py", line
376, in <lambda>
groupby = self.groupby or reduce(lambda a,b:a|b,self.fields)
TypeError: unsupported operand type(s) for |: 'str' and 'str'

[mdipierro]

fixed now.