search: allow mixed regexp patterns and quoted patterns

Created by: rvantonder

Review by commit--

The first commit just makes it possible to do things like reg.*p or "quoted literal thing" by disallowing a heuristic interpretation of a pattern. The exact mechanism (see inline comment) that does this is a workaround that I'll restructure after I've pinned down the behavior by tests.

The second commit helps pin down the behavior with updated tests :-) For my test purposes, I've changed the repos to test against so that they are smaller and frozen to an exact commit, on another GH account.