Apache 2.4 + mod_deflate + etags = HTTP 200 Always
This Apache bug is really annoying. Fortunately, there is a really simple work-around.
Add the following to your Apache configuration:
RequestHeader edit "If-None-Match" "^\"(.*)-gzip\"$" "\"$1\""
Header edit "ETag" "^\"(.*[^g][^z][^i][^p])\"$" "\"$1-gzip\""
This work-around comes from comment #15 on the Bugzilla page. However, you cannot use it as is because as coded it omits the double quotes around the ETag. Credit for the correct work-around goes to this unselected answer to this Stack Overflow question.