fix wallet startup locking up if a lbryumx server is unavailable

CHANGELOG.md

@@ -19,6 +19,7 @@ at anytime.
   * `publish` raising a database error when updating a claim that we don't have a file for (https://github.com/lbryio/lbry/issues/1165)
   * approximations of bid when cast from float to Decimal during publish
   * blob client protocol not tearing itself down properly after a failure (https://github.com/lbryio/lbry/issues/950)
+  * lockup in wallet startup when one or more lbryumx servers are unavailable (https://github.com/lbryio/lbry/issues/1245)
 
 ### Deprecated
   *

lbrynet/core/Wallet.py

@@ -132,6 +132,7 @@ class Wallet(object):
     @defer.inlineCallbacks
     def get_remote_height(self, server, port):
         connected = defer.Deferred()
+        connected.addTimeout(3, reactor, lambda *_: None)
         client = StratumClient(connected)
         reactor.connectTCP(server, port, client)
         yield connected