Fix failure in page processor test
Fix failure in page processor test

Commit 4e94ab99 broke the `PagesTests.test_exact_page_processor_for`
test, because `resolver_match` isn't always set on the `request`
object. Check for that before attempting to set it to unbreak the test.

molokov/mezzanine,frankier/mezzanine,readevalprint/mezzanine,jerivas/mezzanine,molokov/mezzanine,dsanders11/mezzanine,readevalprint/mezzanine,jerivas/mezzanine,stephenmcd/mezzanine,frankier/mezzanine,frankier/mezzanine,stephenmcd/mezzanine,readevalprint/mezzanine,christianwgd/mezzanine,stephenmcd/mezzanine,christianwgd/mezzanine,dsanders11/mezzanine,jerivas/mezzanine,dsanders11/mezzanine,christianwgd/mezzanine,molokov/mezzanine