Master, which version?

[Hannie Dumoleyn <lafeber-dumoleyn2 zonnet nl>]

Sometimes I get confused about which version gnome Master is. Is Master 
always the newest development version?
I have just updated the Dutch translation of gnome-control-center 
Master. Since gnome 3.18 is now stable, I thought this was gnome 3.20, 
but when I enter the command git branch -a I see that gnome-3-18 is not 
listed (conclusion: 3.18 = Master).
Would it be possible to include the version number in the Master name 
like this (e.g. for Gnome 3.18):
//l10n.gnome.org/vertimus/gnome-control-center/master-3-18/
Regards,
Hannie