view CONTRIBUTING @ 33048:46fa46608ca5

namespaces: record and expose whether namespace is built-in

Currently, the templating layer tends to treat each namespace
as a one-off, with explicit usage of {bookmarks}, {tags}, {branch},
etc instead of using {namespaces}. It would be really useful if
we could iterate over namespaces and operate on them generically.
However, some consumers may wish to differentiate namespaces by
whether they are built-in to core Mercurial or provided by extensions.
Expected use cases include ignoring non-built-in namespaces or
emitting a generic label for non-built-in namespaces.

This commit introduces an attribute on namespace instances
that says whether the namespace is "built-in" and then exposes
this to the templating layer.

As part of this, we implement a reusable extension for defining
custom names on each changeset for testing. A second consumer
will be introduced in a subsequent commit.

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