cmd/ftp: exit cleanly on Ctrl-C

bup ftp currently does not handle KeyboardInterrupt exceptions.

Simply call handle_ctrl_c() at the beginning of the file to make the
command exit without a stacktrace.

cmd/ftp-cmd.py

@@ -3,6 +3,9 @@
 from bup import options, git, shquote, vfs
 from bup.helpers import *
 
+handle_ctrl_c()
+
+
 def node_name(text, n):
     if stat.S_ISDIR(n.mode):
         return '%s/' % text