remove unused variable

plugins/keepkey/plugin.py

@@ -1,5 +1,3 @@
-import threading
-
 from binascii import hexlify, unhexlify
 
 from electrum.util import bfh, bh2u
@@ -72,8 +70,6 @@ class KeepKeyCompatiblePlugin(HW_PluginBase):
 
     def __init__(self, parent, config, name):
         HW_PluginBase.__init__(self, parent, config, name)
-        self.main_thread = threading.current_thread()
-        # FIXME: move to base class when Ledger is fixed
         if self.libraries_available:
             self.device_manager().register_devices(self.DEVICE_IDS)
 

plugins/ledger/ledger.py

@@ -573,7 +573,6 @@ class LedgerPlugin(HW_PluginBase):
 
     def get_client(self, keystore, force_pair=True):
         # All client interaction should not be in the main GUI thread
-        #assert self.main_thread != threading.current_thread()
         devmgr = self.device_manager()
         handler = keystore.handler
         with devmgr.hid_lock:

plugins/trezor/trezor.py

@@ -1,5 +1,3 @@
-import threading
-
 from binascii import hexlify, unhexlify
 
 from electrum.util import bfh, bh2u, versiontuple
@@ -93,7 +91,6 @@ class TrezorPlugin(HW_PluginBase):
 
     def __init__(self, parent, config, name):
         HW_PluginBase.__init__(self, parent, config, name)
-        self.main_thread = threading.current_thread()
 
         try:
             # Minimal test if python-trezor is installed