Fix #1513

Forgot to copy a mutated value on save. Added a test to prevent
regression.

tests/test_vox.py

@@ -43,3 +43,25 @@ def test_activate(xonsh_builtins, tmpdir):
     assert xonsh_builtins.__xonsh_env__['VIRTUAL_ENV'] == vox['spam'].env
     vox.deactivate()
     assert 'VIRTUAL_ENV' not in xonsh_builtins.__xonsh_env__
+
+
+@skip_if_on_conda
+def test_path(xonsh_builtins, tmpdir):
+    """
+    Test to make sure Vox properly activates and deactivates by examining $PATH
+    """
+    xonsh_builtins.__xonsh_env__['VIRTUALENV_HOME'] = str(tmpdir)
+    # I consider the case that the user doesn't have a PATH set to be unreasonable
+    xonsh_builtins.__xonsh_env__.setdefault('PATH', [])
+
+    oldpath = list(xonsh_builtins.__xonsh_env__['PATH'])
+    vox = Vox()
+    vox.create('eggs')
+
+    vox.activate('eggs')
+    
+    assert oldpath != xonsh_builtins.__xonsh_env__['PATH']
+    
+    vox.deactivate()
+    
+    assert oldpath == xonsh_builtins.__xonsh_env__['PATH']

xontrib/voxapi.py

@@ -178,7 +178,7 @@ class Vox(collections.abc.Mapping):
         if 'VIRTUAL_ENV' in env:
             self.deactivate()
 
-        type(self).oldvars = {'PATH': env['PATH']}
+        type(self).oldvars = {'PATH': list(env['PATH'])}
         env['PATH'].insert(0, bin_path)
         env['VIRTUAL_ENV'] = env_path
         if 'PYTHONHOME' in env:
@@ -199,6 +199,8 @@ class Vox(collections.abc.Mapping):
             for k, v in type(self).oldvars.items():
                 env[k] = v
             del type(self).oldvars
+        else:
+            print("Warning: No oldvars found")
 
         env.pop('VIRTUAL_ENV')