[RC1] errors popping up with web server - reports uom_id missing

When changing a product form from editable to readonly - before or after saving it:

OpenERP WebClient Error
Client Traceback (most recent call last):
  File "/home/openerp/source/web/trunk/addons/web/common/http.py", line 154, in dispatch
    response["result"] = method(controller, self, **self.params)
  File "/home/openerp/source/web/trunk/addons/web/controllers/main.py", line 873, in load
    return self.fields_view_get(req, model, view_id, view_type, toolbar=toolbar)
  File "/home/openerp/source/web/trunk/addons/web/controllers/main.py", line 762, in fields_view_get
    context = req.session.eval_context(req.context)
  File "/home/openerp/source/web/trunk/addons/web/common/session.py", line 158, in eval_context
    return ccontext.evaluate(ctx)
  File "/home/openerp/source/web/trunk/addons/web/common/nonliterals.py", line 265, in evaluate
    final_context.update(context_to_eval.evaluate(ctx))
  File "/home/openerp/source/web/trunk/addons/web/common/nonliterals.py", line 265, in evaluate
    final_context.update(context_to_eval.evaluate(ctx))
  File "/home/openerp/source/web/trunk/addons/web/common/nonliterals.py", line 185, in evaluate
    raise ValueError('Error during evaluation of this context: "%s", message: "%s"' % (self.get_context_string(), e.message))
ValueError: Error during evaluation of this context: "{'uom_id': uom_id}", message: "name 'uom_id' is not defined"

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Note that uom_id IS defined