Fix bug with lava and flag

Hi, this bug was discovered by Vampy when he working on his next map catfood. Basically when you drop flag into the lava flag started to get continuous damage, event when it returned back to base. So, next time when you pick up the flag, if you just drop it, it will immediately return back to base (no matter where it have fallen or not). This bug was introduced by 24b7dadb commit, also it seems to be dependent on sv_qcphysics (but in a strange way).

With default xon settings this bug isn't appear if you disable sv_qcphysics but with regulars settings for some reason it works even with sv_qcphysics 0.