bundle2: move version of stream clone into part name I don't like having version numbers as part parameters. It means that parts can theoretically vary wildly in their generation and processing semantics. I think that a named part should have consistent behavior over time. In other words, if you need to introduce new functionality or behavior, that should be expressed by inventing a new bundle2 part, not adding functionality to an existing part. This commit applies this advice to the just-introduced stream clone via bundle2 feature. The "version" part parameter is removed. The name of the bundle2 part is now "stream2" instead of "stream" with "version=v2". Differential Revision: https://phab.mercurial-scm.org/D1927