2.4.x patch: http://people.apache.org/~jorton/ap_proxyblock-24x-v2.diff [avoids major MMN bump]
+1: jorton, rjung
+ * mod_proxy_balancer: Restore balancing after a failed worker has
+ recovered when using lbmethod_bybusyness. PR 48735.
+ trunk patch: http://svn.apache.org/viewvc?rev=1366344&view=rev
+ 2.4.x patch: trunk patch works
+ +1: trawick
+
A list of further possible backports can be found at:
http://people.apache.org/~rjung/patches/possible-backports-httpd-trunk-2_4.txt
If you want to propose one of those, please still add them here.