nodemap: introduce append-only incremental update of the persistent data
Rewriting the full nodemap for each transaction has a cost we would like to
avoid. We introduce a new way to write persistent nodemap data by adding new
information at the end for file. Any new and updated block as added at the end
of the file. The last block is the new root node.
With this method, some of the block already on disk get "dereferenced" and
become dead data. In later changesets, We'll start tracking the amount of dead
data to eventually re-generate a full nodemap.
Differential Revision: https://phab.mercurial-scm.org/D7886
== New Features ==
* `hg purge`/`hg clean` can now delete ignored files instead of
untracked files, with the new -i flag.
== New Experimental Features ==
== Bug Fixes ==
== Backwards Compatibility Changes ==
== Internal API Changes ==
* The deprecated `ui.progress()` has now been deleted. Please use
`ui.makeprogress()` instead.
* `hg.merge()` has lost its `abort` argument. Please call
`hg.abortmerge()` directly instead.
* The `*others` argument of `cmdutil.check_incompatible_arguments()`
changed from being varargs argument to being a single collection.