Does 7-CURRENT (aka cvsup tag=.) build under 6-STABLE?

[Randy Bush]

i just upgraded two RELENG_6 boxes to 7-CURRENT last eve.  no prob.
i was silly and broke the union rules by following the instructions
at the bottom of /usr/src/UPDATING.  it is extremely rare that i
have had problems on this path, 4 to 5, 5 to 6, 6 to 7.  have not
tried 7 to 8 yet.

randy