return env to original state

xonsh/environ.py

@@ -10,6 +10,7 @@ import builtins
 import subprocess
 from warnings import warn
 from functools import wraps
+from contextlib import contextmanager
 from collections import MutableMapping, MutableSequence, MutableSet, namedtuple
 
 from xonsh import __version__ as XONSH_VERSION
@@ -281,6 +282,24 @@ class Env(MutableMapping):
         self.ensurers[key] = ens
         return ens
 
+    @contextmanager
+    def swap(self, other):
+        """Provides a context manager for temporarily swapping out certain
+        environment variables with other values. On exit from the context
+        manager, the original values are restored.
+        """
+        old = {}
+        for k, v in other.items():
+            old[k] = self.get(k, NotImplemented)
+            self[k] = v
+        yield self
+        for k, v in old.items():
+            if v is NotImplemented:
+                del self[k]
+            else:
+                self[k] = v
+
+
     #
     # Mutable mapping interface
     #

xonsh/xonfig.py

@@ -93,6 +93,7 @@ def make_fs():
                       path='/foreign_shells/{idx}/funcscmd'),
         StoreNonEmpty("source command [str, default=None]: ",
                       path='/foreign_shells/{idx}/sourcer'),
+        Message(message='')  # inserts a newline
         ])
     return fs
 
@@ -127,8 +128,10 @@ def _wizard(ns):
     env = builtins.__xonsh_env__
     fname = env.get('XONSHCONFIG') if ns.file is None else ns.file
     wiz = make_wizard(default_file=fname, confirm=ns.confirm)
+    tempenv = {'PROMPT': '', 'XONSH_STORE_STDOUT': False}
     pv = PromptVisitor(wiz)
-    pv.visit()
+    with env.swap(tempenv):
+        pv.visit()
 
 
 def _format_human(data):