A PDF-compatible .ai opens on its trim boxes, its editor's artboards,
with the bleed boxes round them as the document's bleed (#1349). A PDF
saved with its editing data (#1345) keeps that data under
AIPDFPrivateData keys, which has_illustrator_data didn't look for, so
such a PDF with a bleed still opened on its crop box: the artboard took
the bleed in and the editing data was refused as being for a different
page. has_illustrator_data now finds either key. has_private_data, which
also decides how a page is clipped, is unchanged.
Test: a_file_with_a_bleed_opens_on_its_artboard_with_the_bleed_round_it
(the .ai case, and the same hand-written file with AIPDFPrivateData).