oops; minor bug in tproxy

thanks to Robin Johnson for catching this.

Note it only happens in one very very specific case: when no command is sent
by the user at all (i.e., "ssh git@host", so even if you don't have this
patch, the workaround is "ssh git@host info");

src/lib/Gitolite/Triggers/TProxy.pm

@@ -95,3 +95,5 @@ sub input {
     # redirect to upstream
     exec( "ssh", $rc{TPROXY_FORWARDS_TO}, "TPROXY_FOR=$user", "SOC=$ENV{SSH_ORIGINAL_COMMAND}" );
 }
+
+1;