rust-index: using `hg::index::Index` in `hg-cpython::dagops`
Hooking `headrevs` to the Rust index is straightforward as long as
we go the `PySharedRef` way. Direct attempts of obtaining a reference
to the inner `hg::index::Index` fail for lifetime reasons: the reference
is bound to the GIL, yet the `as_set` local variable is considered to
be static (the borrow checker clearly does not realize or care that this
set only stores `Revision` values).
In `rank()`, the chosen solution is the simplest as far as `hg-cpython` is
concerned, but it has the defect of removing an implementation
that would be easily adaptable if the core index did implement `RankedGraph`
(returning the same error as long as only `REVLOGV1` is supported), but that
would introduce a direct dependency of `hg-core` on the ``vcsgraph` crate.
$ hg init repo
$ cd repo
$ touch a
$ unset HGUSER
$ echo "[ui]" >> .hg/hgrc
$ echo "username= foo" >> .hg/hgrc
$ echo " bar1" >> .hg/hgrc
$ hg ci -Am m
adding a
abort: username 'foo\nbar1' contains a newline
[255]
$ rm .hg/hgrc
$ HGUSER=`(echo foo; echo bar2)` hg ci -Am m
adding a
abort: username 'foo\nbar2' contains a newline
[255]
$ hg ci -Am m -u "`(echo foo; echo bar3)`"
adding a
transaction abort!
rollback completed
abort: username 'foo\nbar3' contains a newline
[50]