is if_bridge broken?

I am trying to run QEMU on a fairly recent snapshot of HEAD, but it failed with:

    # DISPLAY=:0 qemu -win2k-hack -hda windows.img -boot c -net nic -net tap
    bridge0: creating bridge interface
    ifconfig: SIOCIFCREATE2: Invalid argument
    /etc/qemu-ifup: ERROR: bridge0: failed to create
    /etc/qemu-ifup: could not launch network script
    Could not initialize device 'tap'
    #

At about the same time, `ifconfig bridge0 create' fails with:

Aug 12 09:36:58 gothmog kernel: KLD if_bridge.ko: depends on bridgestp - not available
Aug 12 09:36:58 gothmog giorgos: /etc/qemu-ifup: ERROR: bridge0: failed to create
Aug 12 09:37:17 gothmog kernel: KLD if_bridge.ko: depends on bridgestp - not available
Aug 12 09:48:25 gothmog kernel: KLD if_bridge.ko: depends on bridgestp - not available
Aug 12 09:48:49 gothmog kernel: KLD if_bridge.ko: depends on bridgestp - not available

It appears to have been caused by src/sys/net/if.h revision 1.261:

    date: 2006/07/09 06:04:00;  author: sam;  state: Exp;  lines: +6 -3
    Revise network interface cloning to take an optional opaque
    parameter that can specify configuration parameters:
    o rev cloner api's to add optional parameter block
    o add SIOCCREATE2 that accepts parameter data
    o rev vlan support to use new api (maintain old code)
    
    Reviewed by:    arch_at_

Any idea how if_bridge can be fixed again?