Looks like -"quoted phrase" doesn't remove the phrase from the search results. Link to source of bug: https://www.mediawiki.org/wiki/Topic:S1b3m6774w8qpf8t
Searching for <<"test" -"foo bar">> yields the following query_string query:
<<(all.plain:\"test\" \\-\"foo bar\"~0^1)>> when it really should be something like <<all.plain:\"test\" -all.plain:\"foo bar\">>
Version: unspecified
Severity: normal