view CONTRIBUTING @ 36243:c19e66dacaa1 stable

tests: expand test coverage for updating phases

Consolidating the tests demonstrated that there are behavior
differences when pushing phases between bundle1 and bundle2.

A reason for this is the behavior of legacy pushes where the client
queries the state of phases and then conditionally updates phases
after an "unbundle" is processed. This behavior is expected.

The tests were incomplete because they only tested the case of a
publishing repo. In this commit, we add a variant for a non-publishing
repo. We still see some differences between the legacy and bundle2
exchanges. But they are less pronounced.

The behavior of not firing a pushkey hook when phases are updated as
part of changegroup application feels weird to me. I'm not sure if
this is a feature or a bug. By the time the "pushkey" or "phases"
bundle2 part is applied, the phases have already been moved on
a publishing repository. We fire the "pushkey" hook regardless,
even though it would be a no-op. This is the part that feels the
most buggy.

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