On two of my machines, I got spurious test failures when a test failed

to see that a file removed by a subprocess was actually removed.
Added logic to wait for the file to disappear. :/

Whitespace cleanup. (Although there are a few required trailing white
spaces in buildout.txt.

src/zc/buildout/buildout.txt

@@ -573,6 +573,10 @@ When we rerun the buildout:
     ...
     OSError: [Errno 17] File exists: '/sample-buildout/bin'
 
+.. Wait for the file to really disappear. My linux is weird.
+
+    >>> wait_until("foo goes away", lambda : not os.path.exists('foo'))
+
 we get the same error, but we don't get the directory left behind:
 
     >>> os.path.exists('foo')

src/zc/buildout/testing.py

@@ -183,6 +183,19 @@ def find_python(version):
         "of the Python %(version)s executable before running the tests."
         % {'version': version})
 
+def wait_until(label, func, *args, **kw):
+    if 'timeout' in kw:
+        kw = dict(kw)
+        timeout = kw.pop('timeout')
+    else:
+        timeout = 30
+    deadline = time.time()+timeout
+    while time.time() < deadline:
+        if func(*args, **kw):
+            return
+        time.sleep('.01')
+    raise ValueError('Timed out waiting for: '+label)
+
 def buildoutSetUp(test):
 
     test.globs['__tear_downs'] = __tear_downs = []
@@ -272,6 +285,7 @@ def buildoutSetUp(test):
         bdist_egg = bdist_egg,
         start_server = start_server,
         buildout = os.path.join(sample, 'bin', 'buildout'),
+        wait_until = wait_until,
         ))
 
     zc.buildout.easy_install.prefer_final(prefer_final)