rust-pyo3: new helper for incoming iterables of revisions...
rust-pyo3: new helper for incoming iterables of revisions
The pattern to borrow the core `Index` from the index proxy, and
using it in `rev_pyiter_collect` is frequent enough in what remains
to be converted from `hg-cpython` that it is worth having this direct
helper (and it will neatly enclose the unsafety).
