Please don't do this. Using the same name for a branch as for a tag is
madness. Call it "v2.6.20-stable" or anything else, but don't re-use the
same naming as for tags.

Yes I have done this before, and it took me awhile to realize what was
going on.  It caused me some grief, and a few hours of lost time...Of
course this was back in my earlier days ;)