[horde] Danger Upgrading to Apache 2.4.23

[Andy Dorman]

I am running Horde webmail on Debian with Apache using php-fpm and just 
upgraded all my servers to the latest Apache 2.4.23 yesterday.  Now 
Imp's Dynamic and smartphone/tablet view will not load any mail boxes 
(Basic and mobile minimal views work fine)

I confirmed the problem was caused by the Apache upgrade to 2.4.23 by 
downgrading to 2.4.10 and the problem went away.

The bug that is apparently causing the problem is described here:

https://bz.apache.org/bugzilla/show_bug.cgi?id=59815

-- 
Andy Dorman