relay: attempt to fix race conditions in getRemoteUser calls (#92)

plugins/relay.py

@@ -16,7 +16,9 @@ dbname = "pylinkrelay"
 if confname != 'pylink':
     dbname += '-%s' % confname
 dbname += '.db'
+
 relayusers = defaultdict(dict)
+spawnlocks = defaultdict(threading.Lock)
 
 def relayWhoisHandlers(irc, target):
     user = irc.users[target]
@@ -124,6 +126,7 @@ def getRemoteUser(irc, remoteirc, user, spawnIfMissing=True):
             return remoteirc.pseudoclient.uid
     except AttributeError:  # Network hasn't been initialized yet?
         pass
+    with spawnlocks[irc.name]:
         try:
             u = relayusers[(irc.name, user)][remoteirc.name]
         except KeyError: