Apparently several users already ran into this issue. See e.g.: http://thread.gmane.org/gmane.linux.network/288373 http://lists.suse.de/archive/opensuse-kernel/2014-01/msg00061.html
Bisection led to patch "bridge: cleanup netpoll code" (commit 93d8bf9fb8f39d6d3e461db60f883d9f81006159) as the root cause of this issue.
Fixed by commit dbe173079ab58a444e12dbebe96f5aec1e0bed1a (Feb 6 2014, bridge: fix netconsole setup over bridge).