Catch SIGHUP

This should reduce the chance that a repo we're connected to via ssh
gets interrupted without doing rollback.

mercurial/commands.py

@@ -1199,6 +1199,7 b' def parse(args):'
 
 def dispatch(args):
     signal.signal(signal.SIGTERM, catchterm)
+    signal.signal(signal.SIGHUP, catchterm)
 
     try:
         cmd, func, args, options, cmdoptions = parse(args)