Adapt to the new way that tmux wants unicode be send.

This fixes most unicode using test-cases.

test/vim_interface.py

@@ -172,8 +172,9 @@ class VimInterfaceTmux(VimInterface):
         # to tmux, but it seems like this is all that is needed for now.
         s = s.replace(';', r'\;')
 
-        if PYTHON3:
-            s = s.encode('utf-8')
+        if len(s) == 1:
+            silent_call(['tmux', 'send-keys', '-t', self.session, hex(ord(s))])
+        else:
             silent_call(['tmux', 'send-keys', '-t', self.session, '-l', s])
 
     def send_to_terminal(self, s):

test/vim_test_case.py

@@ -185,7 +185,7 @@ class VimTestCase(unittest.TestCase, TempFileManager):
         if not self.interrupt:
             # Go into insert mode and type the keys but leave Vim some time to
             # react.
-            text = 'i' + self.keys
+            text = u'i' + self.keys.decode("utf-8")
             while text:
                 to_send = None
                 for seq in SEQUENCES: