Automatically reload known_hosts file

JGit caches the contents of the known_hosts file within JSch when
first started, and never attempts to re-read it.  If the contents
change (such as when using Gerrit replication), the new host will
never be found.

On failures, try reloading the knonwn_hosts and retry the
connection, in addition to reloading the credentials.

Change-Id: I980c4f4003f2a48c71b9b47c51e640d1e7742f58
Signed-off-by: Doug Kelly <dougk.ff7@gmail.com>

org.eclipse.jgit/src/org/eclipse/jgit/transport/JschConfigSessionFactory.java

@@ -117,6 +117,9 @@ public abstract class JschConfigSessionFactory extends SshSessionFactory {
 				} catch (JSchException e) {
 					session.disconnect();
 					session = null;
+					// Make sure our known_hosts is not outdated
+					knownHosts(getJSch(hc, fs), fs);
+
 					// if authentication failed maybe credentials changed at the
 					// remote end therefore reset credentials and retry
 					if (credentialsProvider != null && e.getCause() == null