There were a couple of bugs in the implementation of _hydro_pwd
which caused path to be rendered incorrectly:

- if there is a parent directory named the same way as git root, it will
    be "highlighted" instead of the actual git root.
    For example, if you are in `/foo/repo/bar/repo/baz` and the second
    `repo` is git root, the first one will be highlighted.

- if you are in directory named `:` (but not in git repo) it will not be shown.
    For example, if you are in `/tmp/:` you will see `/t/` instead of `/t/:`.

- if one of your parent directories is `:` and you are in git repo,
    the name of the repo will be shown instead of `:`.
    For example, if you are in `/foo/:/bar/repo/baz` you will see
    `/f/repo/b/r/baz` instead of `/f/:/b/repo/baz`.

- if `fish_prompt_pwd_dir_length` is set to `0` and one of the parent
    directories starts with dot, the directory shown will start with dot.
    For example, if you are in `/home/me/.config/fish` you will see
    `.fish` instead of `fish`.

- if you are in a directory that looks like your home directory but isn't,
    it will be replaced with `~`.
    For example, if you are in `/tmp/home/me` you will see `/tmp~`.