Hashing stops on all clients when an invalid account is provided
So, I have this problem with a couple pools-- seems to only effect ones that require an actual username (mining pool hub, minergate, etc).  The basic situation is this: everything is working fine, with a bunch of clients connected and hashing.  Then a new client joins with an invalid account, and everyone dies until the stratum is restarted.  The logs show the following:

miner connected (b5016b21-2a3f-44af-99e5-f8e762db105d)
miner started (b5016b21-2a3f-44af-99e5-f8e762db105d)
pool connection error (b5016b21-2a3f-44af-99e5-f8e762db105d): invalid_site_key
proxy error: undefined
miner disconnected (b5016b21-2a3f-44af-99e5-f8e762db105d)
socket closed (<pool.host>:<pool port>)
connection closed (<pool.host>:<pool port>)

Again, this doesn't happen with anonymous type pools (like supportxmr.com).

Am I doing something wrong, or is this a bug?

Thanks!
