A regex in SearchUpdate was built for ancient pure ISO 8859-1 and looked for \xa0-\xff bytes -- this caused the regex to cut off partway through if there was a char containing a byte in the \x80-\x9f range.
Fixed regex to pass \x80-\xff instead.
Added a test case to SearchUpdateTest which checks for this case (example text run through the update squash algo, then run through preg_replace with a /u param to make sure it gets treated as UTF-8 and checking whether it breaks.)
