reproducible Debian: Add cbxi4a back.

Current stable kernel causes problems, but it is now configured to
stick with older kernel until it can be further debugged.

jenkins-home/offline_nodes

@@ -21,9 +21,6 @@ virt64c-armhf-rb.debian.net
 # probable disk failure
 cbxi4pro0-armhf-rb.debian.net
 cbxi4b-armhf-rb.debian.net
-# not responding to power cycle, needs further investigation
-cbxi4a-armhf-rb.debian.net
-
 
 # Down here nodes are automatically added by the maintenance job when they have
 # been failing their health check or maintenance job for too long.