rhg: Add support for `rhg status --copies`
Copy sources are collected during `status()` rather than after the fact like
in Python, because `status()` takes a `&mut` exclusive reference to the dirstate map
(in order to potentially mutate it for directory mtimes) and returns `Cow<'_, HgPath>`
that borrow the dirstate map.
Even though with `Cow` only some shared borrows remain, the still extend the same
lifetime of the initial `&mut` so the dirstate map cannot be borrowed again
to access copy sources after the fact:
https://doc.rust-lang.org/nomicon/lifetime-mismatch.html#limits-of-lifetimes
Additionally, collecting copy sources during the dirstate tree traversal that
`status()` already does avoids the cost of another traversal or other lookups
(though I haven’t benchmarked that cost).
Differential Revision: https://phab.mercurial-scm.org/D11899
$ for i in aaa zzz; do
> hg init t
> cd t
>
> echo
> echo "-- With $i"
>
> touch file
> hg add file
> hg ci -m "Add"
>
> hg cp file $i
> hg ci -m "a -> $i"
>
> hg cp $i other-file
> echo "different" >> $i
> hg ci -m "$i -> other-file"
>
> hg cp other-file somename
>
> echo "Status":
> hg st -C
> echo
> echo "Diff:"
> hg diff -g
>
> cd ..
> rm -rf t
> done
-- With aaa
Status:
A somename
other-file
Diff:
diff --git a/other-file b/somename
copy from other-file
copy to somename
-- With zzz
Status:
A somename
other-file
Diff:
diff --git a/other-file b/somename
copy from other-file
copy to somename