If two USB sound cards that have the same serial number are plugged in
make sure ID_ID is unique at least during runtime, by including the ALSA
card id in the ID_ID string.
Fixes issues like this one:
http://pulseaudio.org/ticket/661
LABEL="skip_pci"
-ENV{ID_SERIAL}=="?*", ENV{ID_IFACE}=="?*", ENV{ID_ID}="$env{ID_BUS}-$env{ID_SERIAL}-$env{ID_IFACE}"
-ENV{ID_SERIAL}=="?*", ENV{ID_IFACE}=="", ENV{ID_ID}="$env{ID_BUS}-$env{ID_SERIAL}"
+ENV{ID_SERIAL}=="?*", ENV{ID_IFACE}=="?*", ENV{ID_ID}="$env{ID_BUS}-$env{ID_SERIAL}-$env{ID_IFACE}-$attr{id}"
+ENV{ID_SERIAL}=="?*", ENV{ID_IFACE}=="", ENV{ID_ID}="$env{ID_BUS}-$env{ID_SERIAL}-$attr{id}"
ENV{ID_PATH}=="", IMPORT{program}="path_id %p/controlC%n"