Add test to prove bug in Romain's bugfix.

src/zc/buildout/tests.py

@@ -3654,6 +3654,55 @@ def bug_664539_complex_buildout():
     recipe='zc.buildout:debug'
   """
 
+def bug_664539_recipe_updating_options_dict():
+  r"""
+  >>> write('setup.py', '''
+  ... from setuptools import setup
+  ...
+  ... setup(name='foobar',
+  ...       entry_points={
+  ...         'zc.buildout': [
+  ...           'default = foobar:Recipe',
+  ...          ],
+  ...       }
+  ...      )
+  ... ''')
+
+  >>> write('foobar.py', '''
+  ... class Recipe(object):
+  ...
+  ...   def __init__(self, buildout, name, options):
+  ...     options['option'] = '$${value}'
+  ...
+  ...   def install(self):
+  ...     return []
+  ...
+  ...   def update(self):
+  ...     return self.install()
+  ... ''')
+
+  >>> write('buildout.cfg', '''
+  ... [buildout]
+  ... offline = true
+  ... develop = .
+  ... parts = sample
+  ...
+  ... [sample]
+  ... recipe = zc.buildout:debug
+  ... data = ${foobar:option}
+  ...
+  ... [foobar]
+  ... recipe = foobar
+  ... ''')
+
+  >>> print system(buildout),
+  Develop: '/sample-buildout/.'
+  Installing foobar.
+  Installing sample.
+    data='${value}'
+    recipe='zc.buildout:debug'
+  """
+
 ######################################################################
 
 def make_py_with_system_install(make_py, sample_eggs):