There is currently a mechanic that teleports you out of the jail when you try to go in there. Without this, as was the case in earlier versions of Cops and Robbers, the robbers would exploit the fact that the interior of the jail is hardly accessible by cops.
As for the 1 hp, that could have been a coincidence or maybe the teleporting also puts you to 1 hp.
Your second to last sentence seems to suggest that what you did with the jail is an unfair manipulation. I say that breaking the jail door and then dying immediately afterwards (willingly) is a clever way of resetting your wanted level. Whether or not this should be kept should depend on how much it is used. Obviously there is some risks to going to the jail to break the door, with the reward in this case being your freedom. So as far as I'm concerned it's one of those nifty veteran tricks that can stay.