The patch attached should recover the former behaviour, sorry for missing this case.
Oops, sorry, we actually continued on IRC.
Look at the first few commits of http://cgit.osmocom.org/cgit/libosmocore/log/?h=sylvain/for_jolly
They bring in some fixes/cleanups from the kernel for rbtree then something that fixes the timer. This patch keeps the list head intact and just remove the timer from the tree and re-adds it at the right place.
Cheers,
Sylvain