Check that shacache is not influcening buildout runs.

Shacache extension shall not influence buildout run in case of server
malfunction.

upload part is optional.

src/zc/buildout/networkcache.txt

 Using buildout with cache over network
 ======================================
 
+   >>> nc_data = tmpdir('nc_data')
+   >>> nc_url = start_nc(nc_data)
+
 Networkcache in buildout is optional, and during normal run no information
 is shown:
 
@@ -26,20 +29,20 @@ But whenever networkcache configuration is enabled, it is possible to use it:
    ... eggs = demoneeded ==1.2c1
    ...
    ... [networkcache]
-   ... download-cache-url = http://127.0.0.1:8000/shacache
-   ... download-dir-url = http://127.0.0.1:8000/shadir
-   ... upload-cache-url = http://127.0.0.1:8000/shacache
-   ... upload-dir-url = http://127.0.0.1:8000/shadir
+   ... download-cache-url = %(nc_url)sshacache
+   ... download-dir-url = %(nc_url)sshadir
+   ... upload-cache-url = %(nc_url)sshacache
+   ... upload-dir-url = %(nc_url)sshadir
    ... ''' % globals())
    >>> print system(buildout)
    Networkcache enabled.
-   Networkcache download cache: 'http://127.0.0.1:8000/shacache', directory 'http://127.0.0.1:8000/shadir'
-   Networkcache upload cache: 'http://127.0.0.1:8000/shacache', directory 'http://127.0.0.1:8000/shadir'
+   Networkcache download cache: 'http://localhost/shacache', directory 'http://localhost/shadir'
+   Networkcache upload cache: 'http://localhost/shacache', directory 'http://localhost/shadir'
    Installing eggs.
    Getting distribution for 'demoneeded==1.2c1'.
    Downloading demoneeded-1.2c1.zip from network cache.
    Failed to download from network cache demoneeded-1.2c1.zip: 
-   Uploading http://localhost:28922/demoneeded-1.2c1.zip into network cache.
+   Uploading http://localhost/demoneeded-1.2c1.zip into network cache.
    Got demoneeded 1.2c1.
    <BLANKLINE>
 
@@ -51,12 +54,95 @@ Now lets clean up buildout directory:
    >>> remove('.installed.cfg')
 
 And run it again, data will be downloaded from networkcache:
+
    >>> print system(buildout)
    Networkcache enabled.
-   Networkcache download cache: 'http://127.0.0.1:8000/shacache', directory 'http://127.0.0.1:8000/shadir'
-   Networkcache upload cache: 'http://127.0.0.1:8000/shacache', directory 'http://127.0.0.1:8000/shadir'
+   Networkcache download cache: 'http://localhost/shacache', directory 'http://localhost/shadir'
+   Networkcache upload cache: 'http://localhost/shacache', directory 'http://localhost/shadir'
    Installing eggs.
    Getting distribution for 'demoneeded==1.2c1'.
    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', 'demoneeded*'))]
+   [None]
+   >>> remove('.installed.cfg')
+
+As one can see, in case if upload is not working, there is no problem with running buildout:
+
+   >>> 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 = %(nc_url)sshacache
+   ... download-dir-url = %(nc_url)sshadir
+   ... 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://localhost/shacache', directory 'http://localhost/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: 
+   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.
+   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')
+
+Upload is optional, and then no upload will be tried:
+
+   >>> 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 = %(nc_url)sshacache
+   ... download-dir-url = %(nc_url)sshadir
+   ... ''' % globals())
+   >>> print system(buildout)
+   Networkcache enabled.
+   Networkcache download cache: 'http://localhost:27617/shacache', directory 'http://localhost:27617/shadir'
+   Networkcache upload cache: '', directory ''
+   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: 
+   Got demo 0.4c1.
+   Getting distribution for 'demoneeded'.
+   Downloading demoneeded-1.2c1.zip from network cache.
+   Got demoneeded 1.2c1.
+   <BLANKLINE>