Fix generation of enviroment in shell script

rubygems.py

@@ -147,7 +147,7 @@ class Recipe(object):
     def _install_executable(self, path):
         content = ['#!/bin/sh']
         for key, val in self._get_env().items():
-            content.append('export %s=%s' % (key, val))
+            content.append("export %s='%s'" % (key, val))
         content.append('%s "$@"' % path)
         name = os.path.basename(path)
         bindir = self.buildout['buildout']['bin-directory']