future-util: make repeat() exception safe
future-util: make repeat() exception safe

Signed-off-by: Paweł Dziepak <e29bb3265626c60caf76d587cabdfcd8b379ef80@scylladb.com>

avikivity/seastar,syuu1228/seastar,kjniemi/seastar,dreamsxin/seastar,scylladb/seastar,cloudius-systems/seastar,cloudius-systems/seastar,syuu1228/seastar,scylladb/seastar,dreamsxin/seastar,dreamsxin/seastar,avikivity/seastar,cloudius-systems/seastar,scylladb/seastar,kjniemi/seastar,kjniemi/seastar,avikivity/seastar,syuu1228/seastar