When a connection is being activated, nmcli could ask for secrets for another
connection, which might confuse users. We check the request now and only ask
for secrets of connection being activated.

Test case:
$ nmcli con up my-ethernet0
Passwords or encryption keys are required to access the wireless network 'Red Hat'.
Warning: password for '802-1x.identity' not given in 'passwd-file' and nmcli cannot ask without '--ask' option.