Check download cache failure.

src/zc/buildout/networkcache.txt

@@ -137,7 +137,7 @@ Upload is optional, and then no upload will be tried:
    ... ''' % globals())
    >>> print system(buildout)
    Networkcache enabled.
-   Networkcache download cache: 'http://localhost:27617/shacache', directory 'http://localhost:27617/shadir'
+   Networkcache download cache: 'http://localhost/shacache', directory 'http://localhost/shadir'
    Networkcache upload cache: '', directory ''
    Installing eggs.
    Getting distribution for 'demo'.
@@ -148,3 +148,49 @@ Upload is optional, and then no upload will be tried:
    Downloading demoneeded-1.2c1.zip from network cache.
    Got demoneeded 1.2c1.
    <BLANKLINE>
+
+Now lets clean up buildout directory:
+
+   >>> import os, glob
+   >>> [remove(q) for q in glob.glob(os.path.join(sample_buildout, 'eggs', 'demo*'))]
+   [None, None]
+   >>> remove('.installed.cfg')
+
+In case if download cache is failing, original resources are used:
+
+   >>> write(sample_buildout, 'buildout.cfg',
+   ... '''
+   ... [buildout]
+   ...
+   ... networkcache-section = networkcache
+   ... find-links = %(link_server)s
+   ... parts = eggs
+   ...
+   ... [eggs]
+   ... recipe = zc.recipe.egg:eggs
+   ... eggs = demo
+   ...
+   ... [networkcache]
+   ... download-cache-url = http://127.0.0.1:1/shacache
+   ... download-dir-url = http://127.0.0.1:1/shadir
+   ... upload-cache-url = http://127.0.0.1:1/sshacache
+   ... upload-dir-url = http://127.0.0.1:1/sshadir
+   ... ''' % globals())
+   >>> print system(buildout)
+   Networkcache enabled.
+   Networkcache download cache: 'http://127.0.0.1:1/shacache', directory 'http://127.0.0.1:1/shadir'
+   Networkcache upload cache: 'http://127.0.0.1:1/sshacache', directory 'http://127.0.0.1:1/sshadir'
+   Installing eggs.
+   Getting distribution for 'demo'.
+   Downloading demo-0.4c1-py2.7.egg from network cache.
+   Failed to download from network cache demo-0.4c1-py2.7.egg: [Errno 111] Connection refused
+   Uploading http://localhost/demo-0.4c1-py2.7.egg into network cache.
+   Fail to upload file. [Errno 111] Connection refused
+   Got demo 0.4c1.
+   Getting distribution for 'demoneeded'.
+   Downloading demoneeded-1.2c1.zip from network cache.
+   Failed to download from network cache demoneeded-1.2c1.zip: [Errno 111] Connection refused
+   Uploading http://localhost/demoneeded-1.2c1.zip into network cache.
+   Fail to upload file. [Errno 111] Connection refused
+   Got demoneeded 1.2c1.
+   <BLANKLINE>