some flake cleanup

xonsh/base_shell.py

@@ -4,7 +4,6 @@ import io
 import os
 import sys
 import time
-import difflib
 import builtins
 
 from xonsh.tools import (XonshError, print_exception, DefaultNotGiven,
@@ -379,7 +378,7 @@ class BaseShell(object):
             partial_string_info = check_for_partial_string(src)
             in_partial_string = (partial_string_info[0] is not None and
                                  partial_string_info[1] is None)
-            if line == '\n' and not in_partial_string:
+            if (src == '\n' or src.endswith('\n\n')) and not in_partial_string:
                 self.reset_buffer()
                 print_exception()
                 return src, None

xonsh/shell.py

@@ -12,7 +12,7 @@ from xonsh.environ import xonshrc_context
 from xonsh.execer import Execer
 from xonsh.platform import (best_shell_type, has_prompt_toolkit,
                             ptk_version_is_supported)
-from xonsh.tools import XonshError, to_bool_or_int
+from xonsh.tools import XonshError, to_bool_or_int, print_exception
 from xonsh.events import events
 
 

xontrib/bashisms.py

@@ -1,5 +1,6 @@
 """Bash-like interface extensions for xonsh."""
 
+
 @events.on_precommand
 def bash_preproc(cmd):
     return cmd.replace('!!', __xonsh_history__.inps[-1].strip())