[Python-Dev] Iterator version of contextlib.nested

[Terry Reedy]

Raymond Hettinger wrote:

> P.S.  If you switch to PendingDeprecationWarning, the example
> in the docs should probably be switched to show the one valid
> use case (passing in a prepackaged nest of context managers).

It could even suggest that it only be used for this, since it may 
disappear, and that other uses should use the new syntax.  That would 
give people the best chance of writing future-proof code when they can.