DOn't know if this is a repost, but i don't think so..
5 minutes ago i was in a low level battleground to test my little warlock.
I died and i accidentally fell down the hill where the spirit revives people dead.
beacuse the bg went over for ages i decided to quit and get diserter but when i left Bg i don't get the diserter buff, so i think that if u leave Bg when u are a spirit you don't get the diserter buff and u return to the bg hall with full health and mana!
[EDIT] Tried on my main on Av and it works!