Test & implementation for part 1 re: #670

1 files changed, 13 insertions, 6 deletions

diff --git a/paramiko/config.py b/paramiko/config.py
index e18fa4bf..7374eb1a 100644
--- a/paramiko/config.py
+++ b/paramiko/config.py
@@ -76,15 +76,17 @@ class SSHConfig (object):
                     'config': {}
                 }
             elif key == 'proxycommand' and value.lower() == 'none':
-                # Proxycommands of none should not be added as an actual value. (Issue #415)
-                continue
+                # Store 'none' as None; prior to 3.x, it will get stripped out
+                # at the end (for compatibility with issue #415). After 3.x, it
+                # will simply not get stripped, leaving a nice explicit marker.
+                host['config'][key] = None
             else:
                 if value.startswith('"') and value.endswith('"'):
                     value = value[1:-1]
 
-                #identityfile, localforward, remoteforward keys are special cases, since they are allowed to be
-                # specified multiple times and they should be tried in order
-                # of specification.
+                # identityfile, localforward, remoteforward keys are special
+                # cases, since they are allowed to be specified multiple times
+                # and they should be tried in order of specification.
                 if key in ['identityfile', 'localforward', 'remoteforward']:
                     if key in host['config']:
                         host['config'][key].append(value)
@@ -127,10 +129,13 @@ class SSHConfig (object):
                     # else it will reference the original list
                     # in self._config and update that value too
                     # when the extend() is being called.
-                    ret[key] = value[:]
+                    ret[key] = value[:] if value is not None else value
                 elif key == 'identityfile':
                     ret[key].extend(value)
         ret = self._expand_variables(ret, hostname)
+        # TODO: remove in 3.x re #670
+        if 'proxycommand' in ret and ret['proxycommand'] is None:
+            del ret['proxycommand']
         return ret
 
     def get_hostnames(self):
@@ -211,6 +216,8 @@ class SSHConfig (object):
                         }
 
         for k in config:
+            if config[k] is None:
+                continue
             if k in replacements:
                 for find, replace in replacements[k]:
                     if isinstance(config[k], list):