BUG: checks: fix server maintenance exit sequence

Recent commit 62c3be broke maintenance mode by fixing srv_is_usable().
Enabling a disabled server would not re-introduce it into the farm.
The reason is that in set_server_up(), the SRV_MAINTAIN flag is still
present when recounting the servers. The flag was removed late only to
adjust a log message. Keep a copy of the old flag instead and update
SRV_MAINTAIN earlier.

This fix must also be backported to 1.4 (but no release got the regression).
1 file changed