I'm running above mentioned kmail version on openSuSE 13.1 (and the problem 
seems not to occur on Debian):

"Reply" and "Reply to author" don't quote the OP

"Reply to all" and "Reply to mailing list" do quote correctly.

As I don't know what happens to the code between compilations for different 
distributions I don't understand why 3.5.13.2 behaves differently, and it's 
not a problem difficult to live with. Maybe will disappear in 14.

Have a nice day,

Thierry