I was having problems printing purchase RFQs earlier, so I updated my sandbox installation to the latest nightly build.  Now, when I try to print, the browser just says "Waiting for localhost . . ." and never does anything.  Looking at the command line, all I see is this:

> /usr/lib/python2.7/site-packages/odoo-8.0_5d58b55-py2.7.egg/openerp/addons/base/ir/ir_qweb.py(473)render_tag_field()
-> field = record._fields[field_name]

Any ideas?  Is this a bug?