match: fix the rust-side bug in visit_children_set for rootfilesin matchers
The fix is checked by `test_pattern_matcher_visit_children_set` test,
which is what caught the bug in the first place, but also by an end-to-end
test that I made for this purpose.
Accept the new results of Cargo tests
Many of these were already annotated with "FIXME", which is a good sign.
$ hg init repo
$ cd repo
$ echo This is file a1 > a
$ hg add a
$ hg commit -m "commit #0"
$ ls -A
.hg
a
$ echo This is file b1 > b
$ hg add b
$ hg commit -m "commit #1"
$ hg co 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
B should disappear
$ ls -A
.hg
a