Combination with free-text rule, need to fix relevance

[ivanhb]

In the "Advanced Search", Category "Documents", selecting:
file:///Users/ivanhb/opencitations-local/oscar/search.html?text=ambrosini&rule=author_text
and then:
file:///Users/ivanhb/opencitations-local/oscar/search.html?text=ambrosini&rule=author_text&bc=and&text=doppler&rule=any_text

does not work as expected.

This is due to the fact that the second condition (text in document) have a very low score, so the union with the first search will retrieve NULL (the AND connector)