"unmanaged-devices=" lists misbehaves with "except:"

[Martin Pitt]

In yakkety we now ship /usr/lib/NetworkManager/conf.d/10-globally-managed-devices.conf with

   unmanaged-devices=*,except:type:wifi,except:type:wwan

but this now breaks conf.d snippets which want to blacklist an additional interface, such as /run/NetworkManager/conf.d/test-blacklist.conf that does

  unmanaged-devices+=wlan0

resulting in

# NetworkManager --print-config
[...]
unmanaged-devices=*,except:type:wifi,except:type:wwan,wlan0

Intuitively this should ignore wlan0 and all other non-wifi/wwan devices, but with that it *does* manage wlan0.

ProblemType: Bug
DistroRelease: Ubuntu 16.10
Package: network-manager 1.2.2-0ubuntu8
ProcVersionSignature: Ubuntu 4.4.0-34.53-generic 4.4.15
Uname: Linux 4.4.0-34-generic x86_64
ApportVersion: 2.20.3-0ubuntu7
Architecture: amd64
CurrentDesktop: i3
Date: Fri Aug 19 18:23:02 2016
EcryptfsInUse: Yes
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback

 source-directory interfaces.d
NetworkManager.conf:
 [main]
 plugins=ifupdown,keyfile,ofono

 [ifupdown]
 managed=false
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
 WimaxEnabled=true
SourcePackage: network-manager
UpgradeStatus: No upgrade log present (probably fresh install)
nmcli-nm:
 RUNNING VERSION STATE STARTUP CONNECTIVITY NETWORKING WIFI-HW WIFI WWAN-HW WWAN
 running 1.2.2 connected started full enabled enabled enabled enabled enabled