[MRELEASE-946] pushChanges in release:perform

**[James Roper](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=jroper)** opened **[MRELEASE-946](https://issues.apache.org/jira/browse/MRELEASE-946?redirect=false)** and commented

It doesn't make sense to me that the tag should be pushed during the prepare stage when using git - pushing the tag is part of publishing the release. Prior to that, you can tag, commit and undo (change history) as much as you want locally, this is the great thing about a distributed SCM, you don't have to push a tag or other changes until the very last minute, which means if there are any problems while preparing, or even performing the release, you can undo it as if it never happened.

So while prepare does allow you to not push changes, this means that changes have to be pushed manually (or, at least, I haven't seen an option to allow them to be pushed automatically), which to me defeats the purpose of using the release plugin. I think release:perform should, as a last step, have an option to allow pushing changes.

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No further details from [MRELEASE-946](https://issues.apache.org/jira/browse/MRELEASE-946?redirect=false)

Start with the release:perform implementation and its Git handling, then compare how the prepare stage currently treats pushing. Define the option's expected behavior and verify that enabling it pushes changes as the final release step while leaving preparation behavior unchanged.

Written by the indexing model from the issue text.