It seems the assert there is too strict. I don't really understand why
it fails, but I also don't see why the assert is supposed to hold.
Just return in case the device is unmanagable at this point.
The activation shall fail later.
Traceback from a test build of commit a7aca2ab08:
#0 0x00007fdb28ffb643 in g_logv (log_domain=0x7fdb2b584cc9 "NetworkManager", log_level=G_LOG_LEVEL_CRITICAL, format=<optimized out>, args=args@entry=0x7fff10630200) at gmessages.c:1086
#1 0x00007fdb28ffb7bf in g_log (log_domain=log_domain@entry=0x7fdb2b584cc9 "NetworkManager", log_level=log_level@entry=G_LOG_LEVEL_CRITICAL, format=format@entry=0x7fdb29069190 "%s: assertion '%s' failed") at gmessages.c:1119
#2 0x00007fdb28ffb7f9 in g_return_if_fail_warning (log_domain=log_domain@entry=0x7fdb2b584cc9 "NetworkManager", pretty_function=pretty_function@entry=0x7fdb2b54fee0 <__func__.38922> "unmanaged_to_disconnected", expression=expression@entry=0x7fdb2b54d450 "nm_device_get_managed (device, FALSE)") at gmessages.c:1128
#3 0x00007fdb2b36e05b in unmanaged_to_disconnected (device=device@entry=0x7fdb2d2384f0 [NMDeviceVlan]) at src/nm-manager.c:3201
#4 0x00007fdb2b37eb3a in _internal_activate_generic (error=0x7fff106303d0, active=0x7fdb2d1d4550 [NMActRequest], self=0x0) at src/nm-manager.c:3430
#5 0x00007fdb2b37eb3a in _internal_activate_generic (self=self@entry=0x7fdb2d02b090 [NMManager], active=active@entry=0x7fdb2d1d4550 [NMActRequest], error=error@entry=0x7fff10630450) at src/nm-manager.c:3458
#6 0x00007fdb2b37fe90 in _activation_auth_done (active=0x7fdb2d1d4550 [NMActRequest], success=1, error_desc=0x0, user_data1=0x7fdb2d02b090, user_data2=0x7fdb0800bec0) at src/nm-manager.c:3866
#7 0x00007fdb2b4cc9d7 in auth_done (chain=0x7fdb2d17de30, error=0x0, unused=<optimized out>, user_data=<optimized out>) at src/nm-active-connection.c:929
#8 0x00007fdb2b4d6884 in auth_chain_finish (user_data=0x7fdb2d17de30) at src/nm-auth-utils.c:92
#9 0x00007fdb28ff4d7a in g_main_context_dispatch (context=0x7fdb2cff2e00) at gmain.c:3152
#10 0x00007fdb28ff4d7a in g_main_context_dispatch (context=context@entry=0x7fdb2cff2e00) at gmain.c:3767
#11 0x00007fdb28ff50b8 in g_main_context_iterate (context=0x7fdb2cff2e00, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at gmain.c:3838
#12 0x00007fdb28ff538a in g_main_loop_run (loop=0x7fdb2cff2ec0) at gmain.c:4032
#13 0x00007fdb2b349ed7 in main (argc=1, argv=0x7fff106307a8) at src/main.c:438
https://bugzilla.redhat.com/show_bug.cgi?id=1478911