Fix fabric#1753

The tests have a bug when a developer's host has its own ssh config
that sets agent forwarding to the nondefault.

fabric/connection.py

@@ -312,9 +312,7 @@ def __init__(
             forward_agent = self.config.forward_agent
             # But if ssh_config is present, it wins
             if "forwardagent" in self.ssh_config:
-                # TODO: SSHConfig really, seriously needs some love here, god
-                map_ = {"yes": True, "no": False}
-                forward_agent = map_[self.ssh_config["forwardagent"]]
+                forward_agent = self.ssh_config.as_bool("forwardagent")
         #: Whether agent forwarding is enabled.
         self.forward_agent = forward_agent
 

setup.py

@@ -63,7 +63,7 @@
 
     install_requires=[
         'invoke>=1.0,<2.0',
-        'paramiko>=2.4',
+        'paramiko>=2.5',
         'cryptography>=1.1',
     ],
     packages=[package_name],

tests/connection.py

@@ -164,8 +164,9 @@ def shorthand_wins_over_config(self):
 
         class forward_agent:
 
-            def defaults_to_False(self):
-                assert Connection("host").forward_agent is False
+            def defaults_to_connection_config_value(self):
+                conn = Connection("host")
+                assert conn.forward_agent is conn.ssh_config.as_bool("forwardagent")
 
             def accepts_configuration_value(self):
                 config = Config(