[Omake] venv_active_channels in var3

[Aleksey Nogin]

Jason,

The var3 branch used to add (compared to var2) a venv_active_channels
field to venv_runtime. In revs 12122, and 12124 on the 0.9.8.x branch
you have changed how the channels are handled in venv_runtime. Do we
still need the venv_active_channels? Or should I just use the var2 code
(which includes the new 0.9.8.x changes) in var3 now?

Aleksey