dirstate-tree: Add tree traversal/iteration
Like Python’s, Rust’s iterators are "external" in that they are driven
by a caller who calls a `next` method. This is as opposed to "internal"
iterators who drive themselves and call a callback for each item.
Writing an internal iterator traversing a tree is easy with recursion,
but internal iterators cannot rely on the call stack in that way,
they must save in an explicit object all state that they need to be
preserved across two `next` calls.
This algorithm uses a `Vec` as a stack that contains what would be
local variables on the call stack if we could use recursion.
Differential Revision: https://phab.mercurial-scm.org/D10370
Make a narrow clone then archive it
$ . "$TESTDIR/narrow-library.sh"
$ hg init master
$ cd master
$ for x in `$TESTDIR/seq.py 3`; do
> echo $x > "f$x"
> hg add "f$x"
> hg commit -m "Add $x"
> done
$ hg serve -a localhost -p $HGPORT1 -d --pid-file=hg.pid
$ cat hg.pid >> "$DAEMON_PIDS"
$ cd ..
$ hg clone --narrow --include f1 --include f2 http://localhost:$HGPORT1/ narrowclone1
requesting all changes
adding changesets
adding manifests
adding file changes
added 3 changesets with 2 changes to 2 files
new changesets * (glob)
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
The tar should only contain f1 and f2
$ cd narrowclone1
$ hg archive -t tgz repo.tgz
$ tar tfz repo.tgz
repo/f1
repo/f2