Fix up more search tests

Review Request #9176 — Created Sept. 7, 2017 and submitted — Latest diff uploaded

Barret Rennie
Review Board

I missed a few places in the search API where model_filter should have
been passed in instead of filter for filtering search results to a
specific model. In addition, a return clause was indented incorrectly,
causing the user search to sometimes return None. Finally, a erroneous
logging call has been fixed, which caused some test failures.

Ran unit tests.