Ignoring apostrophes in sphinx indexes

Question

In my sphinx config file, I have the following:

ignore_chars: "U+0027"
charset_table: "0..9, a..z, _, A..Z->a..z, U+00C0->a, U+00C1->a,
  U+00C2->a, U+00C3->a, U+00C4->a, U+00C5->a, U+00C7->c, U+00C8->e,
  U+00C9->e, U+00CA->e, U+00CB->e, U+00CC->i, U+00CD->i, U+00CE->i [SNIP]"

(The charset_table entry is from here: http://speeple.com/unicode-maps.txt)

The expected result is that querying kyles will return all records matching kyles and/or kyle's, since I'm telling sphinx to exclude ' (single quote/apos) from the index (ab'cd -> abcd). However, in practice, this is not happening.