Fix handling of find_by_path in transports.

trezorlib/transport_hid.py

@@ -97,7 +97,7 @@ class HidTransport(Transport):
         return devices
 
     @classmethod
-    def find_by_path(cls, path=None):
+    def find_by_path(cls, path):
         if isinstance(path, str):
             path = path.encode()
         path = path.replace(b'%s:' % cls.PATH_PREFIX.encode(), b'')

trezorlib/transport_udp.py

@@ -69,11 +69,8 @@ class UdpTransport(Transport):
         return devices
 
     @classmethod
-    def find_by_path(cls, path=None):
-        if isinstance(path, str):
-            path = path.encode()
-
-        path = path.replace(b'%s:' % cls.PATH_PREFIX.encode(), b'')
+    def find_by_path(cls, path):
+        path = path.replace('%s:' % cls.PATH_PREFIX, '')
         return UdpTransport(path)
 
     def open(self):

trezorlib/transport_webusb.py

@@ -106,7 +106,7 @@ class WebUsbTransport(Transport):
         return devices
 
     @classmethod
-    def find_by_path(cls, path=None):
+    def find_by_path(cls, path):
         path = path.replace('%s:' % cls.PATH_PREFIX, '')  # Remove prefix from __str__()
         for transport in WebUsbTransport.enumerate():
             if path is None or dev_to_str(transport.device) == path: