config: Add a method for setting options

This fixes a regression appeared after Config class became a singleton.
Different parts of pisi tries to create an instance of Config class with
different options. Since it is a singleton, later contructions won't
get the new options. Fix this by implementing a new method for setting
options instance.

pisi/__init__.py

@@ -76,5 +76,5 @@ sys.setdefaultencoding('utf-8')
 
 atexit.register(_cleanup)
 
-ctx.config = pisi.config.Config(pisi.config.Options())
+ctx.config = pisi.config.Config()
 init_logging()

pisi/api.py

@@ -150,7 +150,7 @@ def set_options(options):
            options.verbose     # flag controlling verbosity of the output messages
            options.output_dir  # build and delta operations package output directory
     """
-    ctx.config = pisi.config.Config(options)
+    ctx.config.set_options(options)
 
 def list_needs_restart():
     """

pisi/config.py

@@ -46,7 +46,7 @@ class Config(object):
     __metaclass__ = pisi.util.Singleton
 
     def __init__(self, options = Options()):
-        self.options = options
+        self.set_options(options)
         self.values = pisi.configfile.ConfigurationFile("/etc/pisi/pisi.conf")
 
         destdir = self.get_option('destdir')
@@ -66,6 +66,9 @@ class Config(object):
         # build process.
         self.environ = copy.deepcopy(os.environ)
 
+    def set_options(self, options):
+        self.options = options
+
     def set_option(self, opt, val):
         setattr(self.options, opt, val)