index: add a `get_rev` method (API)...
index: add a `get_rev` method (API)
The new `index.getrev(node)` is to be preferred over using:
`index.nodemap.get(node)`.
This get us closer to be able to remove the `nodemap` attribute of the index.
Differential Revision:
https://phab.mercurial-scm.org/D7326
