APT installed the new version of avahi-daemon, but now /usr/sbin/avahi-daemon has undefined symbols, because APT didn't know that the new version of a library (libdaemon?) is required. A solution would be to add version to the symbols in libdaemon's ABI.

$ rpm -qf /usr/sbin/avahi-daemon
avahi-daemon-0.6.22-alt6
$ ldd -r /usr/sbin/avahi-daemon
undefined symbol: daemon_close_all      (/usr/sbin/avahi-daemon)
        linux-gate.so.1 =>  (0xb7faf000)
        libavahi-common.so.3 => /usr/lib/libavahi-common.so.3 (0xb7f77000)
        libavahi-core.so.5 => /usr/lib/libavahi-core.so.5 (0xb7f46000)
        libdaemon.so.0 => /usr/lib/libdaemon.so.0 (0xb7f40000)
        libexpat.so.1 => /usr/lib/libexpat.so.1 (0xb7f20000)
        libcap.so.1 => /lib/libcap.so.1 (0xb7f1c000)
        libdl.so.2 => /lib/libdl.so.2 (0xb7f18000)
        libdbus-1.so.3 => /usr/lib/libdbus-1.so.3 (0xb7ee1000)
        libc.so.6 => /lib/libc.so.6 (0xb7db9000)
        libpthread.so.0 => /lib/libpthread.so.0 (0xb7da2000)
        /lib/ld-linux.so.2 (0x80000000)
$ rpm -qf /usr/lib/libdaemon.so.0
libdaemon-0.10-alt1
$