network-cache options should not be default

src/zc/buildout/buildout.py

@@ -138,7 +138,6 @@ _buildout_default_options = _annotate_section({
     'socket-timeout': '',
     'unzip': 'false',
     'use-dependency-links': 'true',
-    'network-cache': 'http://127.0.0.1:5001/',
     }, 'DEFAULT_VALUE')
 
 
@@ -363,7 +362,7 @@ class Buildout(UserDict.DictMixin):
                 newest=self.newest,
                 allow_hosts=self._allow_hosts,
                 prefer_final=not self.accept_buildout_test_releases,
-                network_cache=options['network-cache'],
+                network_cache=options.get('network-cache'),
                 )
 
         # Now copy buildout and setuptools eggs, and record destination eggs:

src/zc/buildout/download.py

@@ -181,13 +181,10 @@ class Download(object):
         urllib._urlopener = url_opener
         handle, tmp_path = tempfile.mkstemp(prefix='buildout-')
 
-        sha256sum = get_sha256sum_from_networkcached(self.network_cache,
-                                                          url,
-                                                          self.logger)
         try:
             try:
                 if not download_network_cached(self.network_cache,
-                                            tmp_path, sha256sum, self.logger):
+                                                       tmp_path, self.logger):
 
                     # Download from original url
                     tmp_path, headers = urllib.urlretrieve(url, tmp_path)

src/zc/buildout/networkcache.py

@@ -110,7 +110,7 @@ def get_sha256sum_from_networkcached(network_cache, url, logger):
                                                                ' %s' % str(e))
 
 
-def download_network_cached(network_cache, path, sha256sum, logger):
+def download_network_cached(network_cache, path, logger):
     """Download from a network cache provider
 
     If something fail (providor be offline, or hash_string fail), we ignore
@@ -118,10 +118,14 @@ def download_network_cached(network_cache, path, sha256sum, logger):
 
     return True if download succeeded.
     """
-    if sha256sum is None:
+    if network_cache in (None, '',):
         # Not able to use network cache
         return False
 
+    sha256sum = get_sha256sum_from_networkcached(network_cache,
+                                                 url,
+                                                 self.logger)
+
     url = os.path.join(network_cache, sha256sum)
     logger.info('Downloading from network cache %s' % url)
     try:
@@ -177,6 +181,9 @@ def fetch_from_network_cache(network_cache, location, tmp, logger=None):
     """ Try to download from a network cache and preserve
         original filename.
     """
+    if network_cache in (None, ''):
+      return None
+
     # Make a id from URL
     md5sum = _get_md5_from_url(location)