Merge branch 'master' into pylint

# Conflicts:
#	acme/acme/client.py
#	acme/acme/crypto_util.py
#	acme/acme/standalone.py
#	certbot-apache/certbot_apache/configurator.py
#	certbot-apache/certbot_apache/parser.py
#	certbot-apache/certbot_apache/tests/tls_sni_01_test.py
#	certbot-apache/certbot_apache/tests/util.py
#	certbot-apache/certbot_apache/tls_sni_01.py
#	certbot-nginx/certbot_nginx/configurator.py
#	certbot-nginx/certbot_nginx/parser.py
#	certbot-nginx/certbot_nginx/tests/util.py
#	certbot/account.py
#	certbot/cert_manager.py
#	certbot/cli.py
#	certbot/configuration.py
#	certbot/main.py
#	certbot/ocsp.py
#	certbot/plugins/dns_common_lexicon.py
#	certbot/plugins/standalone.py
#	certbot/plugins/util.py
#	certbot/plugins/webroot.py
#	certbot/tests/auth_handler_test.py
#	certbot/tests/cert_manager_test.py
#	certbot/tests/display/util_test.py
#	certbot/tests/main_test.py
#	certbot/tests/util.py
#	certbot/util.py
#	tox.ini

certbot/plugins/util.py

@@ -9,18 +9,19 @@ logger = logging.getLogger(__name__)
 def get_prefixes(path):
     """Retrieves all possible path prefixes of a path, in descending order
     of length. For instance,
-        /a/b/c/ => ['/a/b/c/', '/a/b/c', '/a/b', '/a', '/']
+        (linux) /a/b/c returns ['/a/b/c', '/a/b', '/a', '/']
+        (windows) C:\\a\\b\\c returns ['C:\\a\\b\\c', 'C:\\a\\b', 'C:\\a', 'C:']
     :param str path: the path to break into prefixes
 
     :returns: all possible path prefixes of given path in descending order
     :rtype: `list` of `str`
     """
-    prefix = path
+    prefix = os.path.normpath(path)
     prefixes = []
     while prefix:
         prefixes.append(prefix)
         prefix, _ = os.path.split(prefix)
-        # break once we hit '/'
+        # break once we hit the root path
         if prefix == prefixes[-1]:
             break
     return prefixes
@@ -49,7 +50,8 @@ def path_surgery(cmd):
 
     if util.exe_exists(cmd):
         return True
-    expanded = " expanded" if any(added) else ""
-    logger.warning("Failed to find executable %s in%s PATH: %s", cmd,
-                   expanded, path)
-    return False
+    else:
+        expanded = " expanded" if any(added) else ""
+        logger.debug("Failed to find executable %s in%s PATH: %s", cmd,
+                     expanded, path)
+        return False