issue34138: fix implementation of utf8 append

Author: gordonmessmer

Lib/imaplib.py

@@ -966,7 +966,7 @@ def _command(self, name, *args):
             else:
                 literator = None
                 if self.utf8_enabled:
-                    data = data + bytes('UTF8 (~{%s}' % len(literal), self._encoding)
+                    data = data + bytes(' UTF8 (~{%s}' % len(literal), self._encoding)
                     literal = literal + b')'
                 else:
                     data = data + bytes(' {%s}' % len(literal), self._encoding)