Doesn't reconnect to wifi after resuming from suspend

[Ferry Toth <ftoth telfort nl>]

On my home wifi network I have 1 2.4GHz and 1 5GHz AP (is actually 1 fritz 
box).

With one machine (chromebook running kubuntu 14.10 and AR9462 abgn wifi)

When automatically reconnecting to 5GHz after resume half of the time the 
connection fails and retries indefinitely. It seems to fail more when moving 
the laptop to another location in house while it sleeps (so the list of 
visible networks actually changes).

When this happens it is almost impossible to reconnect manually.

(what works sometimes is disconnecting the connection that is building, 
disable the wifi, enable again, wait a bit then manually connect to the 
other (2.4GHz) AP)

Strangely: disabling autoconnect on resume and then manually connecting 
always works.

Other strange thing: Another machine (NUC with intel wifi and same kubuntu 
14.10) always works.

To me, it seems to be some interference between rescanning and connecting.

I have no idea what is the difference in the state machine when 
autoconnecting vs. manual.

I've provided log's on bugzilla 
https://bugzilla.gnome.org/show_bug.cgi?id=726121

Any suggestions are highly appreciated.