rust-cpython: add panicking version of borrow_mut() and use it
The original borrow_mut() is renamed to try_borrow_mut().
Since leak_immutable() no longer incref the borrow count, the caller should
know if the underlying value is borrowed or not. No Python world is involved.
That's why we can simply use the panicking borrow_mut().
https://bz.mercurial-scm.org/1502
Initialize repository
$ hg init foo
$ touch foo/a && hg -R foo commit -A -m "added a"
adding a
$ hg clone foo foo1
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo "bar" > foo1/a && hg -R foo1 commit -m "edit a in foo1"
$ echo "hi" > foo/a && hg -R foo commit -m "edited a foo"
$ hg -R foo1 pull
pulling from $TESTTMP/foo
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
new changesets 273d008d6e8e
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg -R foo1 book branchy
$ hg -R foo1 book
* branchy 1:e3e522925eff
Pull. Bookmark should not jump to new head.
$ echo "there" >> foo/a && hg -R foo commit -m "edited a again"
$ hg -R foo1 pull
pulling from $TESTTMP/foo
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
new changesets 84a798d48b17
(run 'hg update' to get a working copy)
$ hg -R foo1 book
* branchy 1:e3e522925eff