3rd+ page of Advanced Search mishandles apostrophes

An Advanced Search for all authors with surnames starting with [O'] finds only 199 entries, though there are obviously more as search sorts authors by last, then first name, and the list stops at "Mxxx O'xxx." The affected script, aa_search.py, adds too many backslashes to escape apostrophes, e.g. http://127.0.0.1/cgi-bin/edit/aa_search.cgi?author_canonical%3Do\\\%27+record%3D200+sort%3Dauthor_canonical