Merge r1619835, r1620461 from trunk:

don't let handlers start with r->status = 304 during a failed revalidation

PR56881



Fix typo in comment.

Submitted by: covener, rjung
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1627745 13f79535-47bb-0310-9956-ffa450edef68