dirstate-tree: Make `DirstateMap` borrow from a bytes buffer
… that has the contents of the `.hg/dirstate` file.
This only applies to the tree-based flavor of `DirstateMap`.
For now only the entire `&[u8]` slice is stored, so this is not useful yet.
Adding a lifetime parameter to the `DirstateMap` struct (in hg-core) makes
Python bindings non-trivial because we keep that struct in a Python object
that has a dynamic lifetime tied to Python’s reference-counting and GC.
As long as we keep the `PyBytes` that owns the borrowed bytes buffer next to
the borrowing struct, the buffer will live long enough for the borrows to stay
valid. However this relationship cannot be expressed in safe Rust code in a
way that would statisfy they borrow-checker. We use `unsafe` code to erase
that lifetime parameter, and encapsulate it in a safe abstraction similar to
the owning-ref crate: https://docs.rs/owning_ref/
Differential Revision: https://phab.mercurial-scm.org/D10557
Test update.requiredest
$ cd $TESTTMP
$ cat >> $HGRCPATH <<EOF
> [commands]
> update.requiredest = True
> EOF
$ hg init repo
$ cd repo
$ echo a >> a
$ hg commit -qAm aa
$ hg up
abort: you must specify a destination
(for example: hg update ".::")
[10]
$ hg up .
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ HGPLAIN=1 hg up
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg --config commands.update.requiredest=False up
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd ..
Check update.requiredest interaction with pull --update
$ hg clone repo clone
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd repo
$ echo a >> a
$ hg commit -qAm aa
$ cd ../clone
$ hg pull --update
abort: update destination required by configuration
(use hg pull followed by hg update DEST)
[10]
$ cd ..
update.requiredest should silent the "hg update" text after pull
$ hg init repo1
$ cd repo1
$ hg pull ../repo
pulling from ../repo
requesting all changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
new changesets 8f0162e483d0:048c2cb95949