[manual] Rename /home/humbug to /home/zulip.

This may require just doing an mv on the home directory, plus changing
the home directory in /etc/passwd.  It should of course be done carefully.

(imported from commit 660997d897ee6d33563af74f0fc5d4267a911755)

bots/check-mirroring

@@ -22,7 +22,7 @@ parser.add_option('--sharded',
                   action='store_true')
 parser.add_option('--root-path',
                   dest='root_path',
-                  default="/home/humbug",
+                  default="/home/zulip",
                   action='store')
 (options, args) = parser.parse_args()