nixops: fix format exception from upstream nixops

Without this our nixops doesn't build

pkgs/nixops/release.nix.patch

@@ -43,7 +43,6 @@
                                     ('destDir',     'string'),
                                     ('user',        'string'),
                                     ('group',       'string'),
-
 --- a/nixops/ssh_util.py
 +++ b/nixops/ssh_util.py
 @@ -278,6 +278,7 @@ class SSH(object):
@@ -54,3 +53,15 @@
          master = self.get_master(flags, timeout, user)
          flags = flags + self._get_flags()
          if logged:
+
+--- a/nixops/deployment.py
++++ b/nixops/deployment.py
+@@ -748,6 +748,6 @@
+                 if res == 100 or force_reboot or m.state == m.RESCUE:
+                     if not allow_reboot and not force_reboot:
+                         raise Exception("the new configuration requires a "
+-                                        "reboot to take effect (hint: use "
++                                        "reboot of '{}' to take effect (hint: use "
+                                         "‘--allow-reboot’)".format(m.name))
+                     m.reboot_sync()
+                     res = 0