D5361: rebase: fix path auditing to audit path relative to repo root

[Yuya Nishihara]

>   Before this patch, when rebasing a file called "foo/bar", we would
>   check e.g. if "/foo" (i.e. rooted at the file system root) was a
>   symlink. That's clearly not what we meant to do. I haven't added a
>   test case because I don't know to test it.

This probably fixes the issue5818.

https://bz.mercurial-scm.org/show_bug.cgi?id=5818

>          # Test the other direction -- that this path from p2 isn't a directory
> -        # in p1 (test that p1 doesn't any paths matching `path/*`).
> -        match = matchmod.match('/', '', [path + '/'], default=b'relpath')
> +        # in p1 (test that p1 doesn't have any paths matching `path/*`).
> +        match = self.match(pats=[path + '/'], default=b'relpath')

'relpath' means relative to cwd. It should be `default=b'path'` or simply
`scmutil.matchfiles()`.